IOS的框架介绍

<wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)">iPhone OS(现在叫iOS)是iPhone, iPod touch 和 iPad 设备的操作系统.</span></wbr>

<wbr><wbr><wbr>1,Core OS:</wbr></wbr></wbr> <wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)">是用FreeBSD和Mach所改写的Darwin, 是开源、符合POSIX标准的一个Unix核心。这一层包含或者说是提供了整个iPhone OS的一些基础功能，比如：硬件驱动, 内存管理，程序管理，线程管理（POSIX），文件系统，网络（BSD Socket）,以及标准输入输出等等，所有这些功能都会通过C语言的API来提供。另外，值得一题的是，这一层最具有UNIX色彩，如果你需要把 UNIX上所开发的程序移植到iPhone上，多半都会使用到Core OS的API.</span> <div style="font-family:Helvetica; font-size:14px"><br style="color:rgb(70,70,70); font-family:simsun; line-height:21px"></div> <span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)">核心OS层的驱动也提供了硬件和系统框架之间的接口。然而，由于安全的考虑，只有有限的系统框架类能访问内核和驱动。</span> <div style="font-family:Helvetica; font-size:14px"><br style="color:rgb(70,70,70); font-family:simsun; line-height:21px"></div> <span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)">iPhone OS提供了许多访问操作系统低层功能的接口集，iPhone 应用通过LibSystem库来访问这些功能，这些接口集如下所示：</span> <div style="font-family:Helvetica; font-size:14px"><br style="color:rgb(70,70,70); font-family:simsun; line-height:21px"></div> <span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)">线程（POSIX线程）；</span> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>网络（BSD sockets）；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>文件系统访问；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>标准I/O；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>Bonjour和DNS服务；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>现场信息（Locale Information）；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>内存分配；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>数学计算。</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)">许多Core OS技术的头文件位于目录&lt;iPhoneSDK&gt;/usr/include/，iPhoneSDK是SDK的安装目录。</span> <div style="font-family:Helvetica; font-size:14px"><br style="color:rgb(70,70,70); font-family:simsun; line-height:21px"></div> <div style="font-family:Helvetica; font-size:14px"><br style="color:rgb(70,70,70); font-family:simsun; line-height:21px"></div> <span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"><strong><wbr>2,Core Services:<br><wbr><wbr></wbr></wbr></wbr></strong></span><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)">Core Services在Core OS基础上提供了更为丰富的功能， 它包含了Foundation.Framework和Core Foundation.Framework, 之所以叫Foundation ,就是因为它提供了一系列处理字串，排列，组合，日历，时间等等的基本功能。Foundation是属于Objective-C的API，Core Fundation是属于C的API。另外Core servieces还提供了其他的功能，比如：</span> <div style="font-family:Helvetica; font-size:14px"><br style="color:rgb(70,70,70); font-family:simsun; line-height:21px"></div> <span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)">Security, Core Location, SQLite, 和Address Book. 其中Security是用来处理认证，密码管理，按安全性管理的； Core Location是用来处理GPS定位的；SQLLite是轻量级的数据库，而AddressBook则用来处理电话薄资料的。下面是具体介绍:</span><span style="font-size:14px; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"><strong><br><wbr><wbr></wbr></wbr></strong></span><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px">（1）电话本</span> <div style="font-family:Helvetica; font-size:14px"><br style="color:rgb(70,70,70); font-family:simsun; line-height:21px"></div> <span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)">电话本框架（AddressBook.framework）提供了保存在手机设备中的电话本编程接口。开发者能使用该框架访问和修改存储在用户联系 人数据库里的记录。例如，一个聊天程序可以使用该框架获得可能的联系人列表，启动聊天的进程（Process），并在视图上显示这些联系人信息等。</span> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <strong><wbr><wbr><wbr>（2）核心基础框架</wbr></wbr></wbr></strong><br></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>核心基础框架（CoreFoundation.framework）是基于C语言的接口集，提供iPhone应用的基本数据管理和服务功能。该框架 支持如下功能：</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>Collection数据类型（Arrays、 Sets等）；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>Bundles；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>字符串管理；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>日期和时间管理；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>原始数据块管理；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>首选项管理；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>URL和Stream操作；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>线程和运行循环（Run Loops）；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>端口和Socket通信。</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>核心基础框架与基础框架是紧密相关的，它们为相同的基本功能提供了Objective-C接口。如果开发者混合使用Foundation Objects 和Core Foundation类型，就能充分利用存在两个框架中的"toll-free bridging"。toll-free bridging意味着开发者能使用这两个框架中的任何一个的核心基础和基础类型，例如Collection和字符串类型等。每个框架中的类和数据类型的 描述注明该对象是否支持toll-free bridged。如果是，它与哪个对象桥接（toll-free bridged）。</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <strong><wbr><wbr><wbr>（3）CFNetwork</wbr></wbr></wbr></strong></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>CFNetwork框架（CFNetwork.framework）是一组高性能的C语言接口集，提供网络协议的面向对象的抽象。开发者可以使用 CFNetwork框架操作协议栈，并且可以访问低层的结构如BSD Sockets等。同时，开发者也能简化与FTP和HTTP服务器的通信，或解析DNS等任务。使用CFNetwork框架实现的任务如下所示：</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>BSD Sockets；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>利用SSL或TLS创建加密连接；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>解析DNS Hosts；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>解析HTTP协议，鉴别HTTP和HTTPS服务器；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>在FTP服务器工作；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>发布、解析和浏览Bonjour服务。</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <strong><wbr><wbr><wbr>（4）核心位置框架（Core Location Framework）</wbr></wbr></wbr></strong></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>核心位置框架（CoreLocation.framework）主要获得手机设备当前的经纬度，核心位置框架利用附近的GPS、蜂窝基站或Wi- Fi信号信息测量用户的当前位置。iPhone地图应用使用这个功能在地图上显示用户的当前位置。开发者能融合这个技术到自己的应用中，给用户提供一些位 置信息服务。例如可以提供一个服务：基于用户的当前位置，查找附近的餐馆、商店或设备等。</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <strong><wbr><wbr><wbr>（5）安全框架（Security Framework）</wbr></wbr></wbr></strong></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>iPhone OS除了内置的安全特性外，还提供了外部安全框架（Security.framework），从而确保应用数据的安全性。该框架提供了管理证书、公钥/私 钥对和信任策略等的接口。它支持产生加密安全的伪随机数，也支持保存在**链的证书和**。对于用户敏感的数据，它是安全的知识库（Secure Repository）。CommonCrypto接口也支持对称加密、HMAC和数据摘要。在iPhone OS里没有OpenSSL库，但是数据摘要提供的功能在本质上与OpenSSL库提供的功能是一致的。</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <strong><wbr><wbr>（6）SQLite</wbr></wbr></strong></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>iPhone应用中可以嵌入一个小型SQL数据库SQLite，而不需要在远端运行另一个数据库服务器。开发者可以创建本地数据库文件，并管理这些 文件中的表格和记录。数据库SQLite为通用的目的而设计，但仍可以优化为快速访问数据库记录。访问数据库SQLite的头文件位 于&lt;iPhoneSDK&gt;/usr/include/sqlite3.h，其中&lt;iPhoneSDK&gt;是SDK安装的目标路径。</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <strong><wbr><wbr><wbr>（7）支持XML</wbr></wbr></wbr></strong></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>基础框架提供NSXMLParser类，解析XML文档元素。libXML2库提供操作XML内容的功能，这个开放源代码的库可以快速解析和编辑 XML数据，并且转换XML内容到HTML。访问libXML2库的头文件位于目录&lt;iPhoneSDK&gt;/usr/include /libxml2/，其中&lt;iPhoneSDK&gt;是SDK安装的目标目录。</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><span style="word-wrap:normal; word-break:normal; font-weight:bold">3,Media</span></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr>如同其名，Media层提供了图片，音乐，影片等多媒体功能。图像分为2D图像和3D图像， 前者由Quartz2D来支持，后者则是用OpenglES.与音乐对应的模组是Core Audio和OpenAL, Media Player 实现了影片的播放， 而最后还提供了Core Animation来对强大动画的支持。具体介绍如下:</wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><strong>（1）图像技术（Graphics Technologies）</strong></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>高质量图像是所有iPhone应用的一个重要的组成部分。任何时候，开发者可以采用UIKit 框架中已有的视图和功能以及预定义的图像来开发iPhone应用。然而，当UIKit 框架中的视图和功能不能满足需求时，开发者可以应用下面描述的技术和方法来制作视图。</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>① Quartz。核心图像框架（CoreGraphics.framework）包含了Quartz 2D画图API，Quartz与在Mac OS中采用的矢量图画引擎是一样先进的。Quartz支持基于路径（Path-based）画图、抗混淆（Anti-aliased）重载、梯度 （Gradients）、图像（Images）、颜色（Colors）、坐标空间转换（Coordinate-space Transformations）、pdf文档创建、显示和解析。虽然API是基于C语言的，它采用基于对象的抽象表征基础画图对象，使得图像内容易于保存和复用。</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>② 核心动画（Core Animation）。Quartz核心框架（QuartzCore.framework）包含CoreAnimation接口，Core Animation是一种高级动画和合成技术，它用优化的重载路径（Rendering Path）实现复杂的动画和虚拟效果。它用一种高层的Objective-C接口配置动画和效果，然后重载在硬件上获得较好的性能。Core Animation集成到iPhone OS 的许多部分，包括UIKit类如UIView，提供许多标准系统行为的动画。开发者也能利用这个框架中的Objective-C接口创建客户化的动画。</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>③ OpenGL ES。OpenGL ES框架（OpenGLES.framework）符合OpenGL ES v1.1规范，它提供了一种绘画2D和3D内容的工具。OpenGL ES 框架是基于Ｃ语言的框架，与硬件设备紧密相关，为全屏游戏类应用提供高帧率（high frame rates）。开发者总是要使用OpenGL框架的EAGL接口，EAGL接口是OpenGL ES框架的一部分，它提供了应用的OpenGL ES画图代码和本地窗口对象的接口。</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <strong><wbr><wbr><wbr><wbr><wbr>（2）音频技术（Audio Technologies）</wbr></wbr></wbr></wbr></wbr></strong><br></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr>iPhone OS的音频技术为用户提供了丰富的音频体验。它包括音频回放，高质量的录音和触发设备的振动功能等。</wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr>iPhone OS的音频技术支持如下音频格式：AAC、Apple Lossless（ALAC）、A-law、IMA/ADPCM（IMA4）、Linear PCM、μ-law和Core Audio等。</wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr>① 核心音频（Core Audio Family）。核心音频框架家族（Core Audio family of frameworks）提供了音频的本地支持，如表16-1所示。Core Audio是一个基于C语言的接口，并支持立体声（Stereo Audio）。开发能采用iPhone OS 的Core Audio框架在iPhone 应用中产生、录制、混合和播放音频。开发者也能通过核心音频访问手机设备的振动功能。</wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr>核心音频框架:</wbr></wbr></wbr></wbr></wbr></wbr></p> <div align="center" style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"> <table border="1" cellpadding="0" cellspacing="0" style="margin:0px; padding:0px; border:medium none; border-collapse:collapse"><tbody> <tr style="height:17pt"> <td style="margin:0px; padding:0cm 5.4pt; font-family:Verdana,宋体,sans-serif; line-height:18px; border:1pt solid windowtext; height:17pt; background-color:transparent"> <p style="margin:0cm 0cm 0pt; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal"> <span style="word-wrap:normal; word-break:normal; line-height:21px; font-size:10.5pt; font-family:宋体">框架（</span><span lang="EN-US" style="word-wrap:normal; word-break:normal; line-height:21px; font-size:10.5pt">Framework</span><span style="word-wrap:normal; word-break:normal; line-height:21px; font-size:10.5pt; font-family:宋体">）</span></p> </td> <td style="margin:0px; padding:0cm 5.4pt; font-family:Verdana,宋体,sans-serif; line-height:18px; border-width:1pt 1pt 1pt medium; border-style:solid solid solid none; border-color:windowtext windowtext windowtext rgb(236,233,216); height:17pt; background-color:transparent"> <p style="margin:0cm 0cm 0pt; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal"> <span style="word-wrap:normal; word-break:normal; line-height:21px; font-size:10.5pt; font-family:宋体">服务（</span><span lang="EN-US" style="word-wrap:normal; word-break:normal; line-height:21px; font-size:10.5pt">Service</span><span style="word-wrap:normal; word-break:normal; line-height:21px; font-size:10.5pt; font-family:宋体">）</span></p> </td> </tr> <tr style="height:17pt"> <td valign="top" style="margin:0px; padding:0cm 5.4pt; font-family:Verdana,宋体,sans-serif; line-height:18px; border-width:medium 1pt 1pt; border-style:none solid solid; border-color:rgb(236,233,216) windowtext windowtext; height:17pt; background-color:transparent"> <p style="margin:0cm 0cm 0pt; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal"> <span lang="EN-US" style="word-wrap:normal; word-break:normal; line-height:21px; font-size:10.5pt">CoreAudio.framework</span></p> </td> <td valign="top" style="margin:0px; padding:0cm 5.4pt; font-family:Verdana,宋体,sans-serif; line-height:18px; border-width:medium 1pt 1pt medium; border-style:none solid solid none; border-color:rgb(236,233,216) windowtext windowtext rgb(236,233,216); height:17pt; background-color:transparent"> <p style="margin:0cm 0cm 0pt; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal"> <span style="word-wrap:normal; word-break:normal; line-height:21px; font-size:10.5pt; font-family:宋体">定义核心音频的音频数据类型</span></p> </td> </tr> <tr style="height:17pt"> <td valign="top" style="margin:0px; padding:0cm 5.4pt; font-family:Verdana,宋体,sans-serif; line-height:18px; border-width:medium 1pt 1pt; border-style:none solid solid; border-color:rgb(236,233,216) windowtext windowtext; height:17pt; background-color:transparent"> <p style="margin:0cm 0cm 0pt; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal"> <span lang="EN-US" style="word-wrap:normal; word-break:normal; line-height:21px; font-size:10.5pt">AudioUnit.framework</span></p> </td> <td valign="top" style="margin:0px; padding:0cm 5.4pt; font-family:Verdana,宋体,sans-serif; line-height:18px; border-width:medium 1pt 1pt medium; border-style:none solid solid none; border-color:rgb(236,233,216) windowtext windowtext rgb(236,233,216); height:17pt; background-color:transparent"> <p style="margin:0cm 0cm 0pt; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal"> <span style="word-wrap:normal; word-break:normal; line-height:21px; font-size:10.5pt; font-family:宋体">提供音频和流媒体文件的</span></p> <p style="margin:0cm 0cm 0pt; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal"> <span style="word-wrap:normal; word-break:normal; line-height:21px; font-size:10.5pt; font-family:宋体">回放和录制，并且管理音</span></p> <p style="margin:0cm 0cm 0pt; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal"> <span style="word-wrap:normal; word-break:normal; line-height:21px; font-size:10.5pt; font-family:宋体">频文件和播放提示声音</span></p> </td> </tr> <tr style="height:17pt"> <td valign="top" style="margin:0px; padding:0cm 5.4pt; font-family:Verdana,宋体,sans-serif; line-height:18px; border-width:medium 1pt 1pt; border-style:none solid solid; border-color:rgb(236,233,216) windowtext windowtext; height:17pt; background-color:transparent"> <p style="margin:0cm 0cm 0pt; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal"> <span lang="EN-US" style="word-wrap:normal; word-break:normal; line-height:21px; font-size:10.5pt">AudioToolbox.framework</span></p> </td> <td valign="top" style="margin:0px; padding:0cm 5.4pt; font-family:Verdana,宋体,sans-serif; line-height:18px; border-width:medium 1pt 1pt medium; border-style:none solid solid none; border-color:rgb(236,233,216) windowtext windowtext rgb(236,233,216); height:17pt; background-color:transparent"> <p style="margin:0cm 0cm 0pt; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal"> <span style="word-wrap:normal; word-break:normal; line-height:21px; font-size:10.5pt; font-family:宋体">提供使用内置音频单元服务，</span></p> <p style="margin:0cm 0cm 0pt; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal"> <span style="word-wrap:normal; word-break:normal; line-height:21px; font-size:10.5pt; font-family:宋体">音频处理模块</span></p> </td> </tr> </tbody></table> </div> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <br><wbr><wbr><wbr><wbr><wbr><wbr><wbr>② OpenAL。iPhone OS 也支持开放音频库（Open Audio Library， OpenAL）。OpenAL是一个跨平台的标准，它能传递位置音频（Positional Audio）。开发者能应用OpenAL在需要位置音频输出的游戏或其他应用中实现高性能、高质量的音频。</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>由于OpenAL是一个跨平台的标准，采用OpenAL的代码模块可以平滑地移植到其他平台。</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <strong><wbr><wbr><wbr><wbr><wbr><wbr>（3）视频技术（Video Technologies）</wbr></wbr></wbr></wbr></wbr></wbr></strong></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>iPhone OS通过媒体播放框架（MediaPlayer.framework）支持全屏视频回放。媒体播放框架支持的视频文件格式包括.mov, .mp4,.m4v和.3gp，并应用如下压缩标准：</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>① H.264 Baseline Profile Level 3.0 video，在30 f/s 的情况下分辨率达到640×480像素。注意：不支持B frames；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>② MPEG4规范的视频部分；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>③ 众多的音频格式，包含在音频技术的列表里，如AAC、Apple Lossless （ALAC）、A-law、IMA/ADPCM（IMA4）、线性PCM、μ-law和Core Audio等。<wbr><wbr><wbr><wbr><wbr><wbr><br></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <span style="word-wrap:normal; word-break:normal; font-weight:bold"><wbr><wbr><wbr><wbr><wbr><wbr><wbr>4,Cocoa Touch</wbr></wbr></wbr></wbr></wbr></wbr></wbr></span></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>最上面一层是Cocoa Touch，它是Objective-C的API, 其中最核心的部分是UIKit.Framework,应用程序界面上的各种组件，全是由它来提供呈现的，除此之外它还负责处理屏幕上的多点触摸事件，文字的输出，图片,网页的显示，相机或文件的存取，以及加速感应的部分等。具体介绍如下:</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><strong>（1）UIKit框架</strong></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>UIKit框架（UIKit.framework）包含Objective-C程序接口，提供实现图形，事件驱动的iPhone应用的关键架构。 iPhone OS中的每一个应用采用这个框架实现如下核心功能：</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>应用管理；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>支持图形和窗口；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>支持触摸事件处理；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>用户接口管理；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>提供用来表征标准系统视图和控件的对象；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>支持文本和Web内容；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>通过URL scheme与其他应用的集成。</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>为提供基础性代码建立应用，UIKit也支持一些与设备相关的特殊功能，如下所示：</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>加速计数据；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>内建Camera；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>用户图片库；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr>设备名称和模式信息。</wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <strong><wbr><wbr><wbr><wbr><wbr>（2）基础框架（Foundation Framework）</wbr></wbr></wbr></wbr></wbr></strong></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>基础框架（Foundation.framework）支持如下功能：</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>Collection数据类型（包括Arrays、Sets）；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>Bundles；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>字符串管理；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>日期和时间管理；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>原始数据块管理；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>首选项管理；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>线程和循环；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>URL和Stream处理；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>Bonjour；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>通信端口管理；</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr><wbr>国际化。</wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <strong><wbr><wbr><wbr><wbr><wbr>（3）电话本UI框架（Address Book UI Framework）</wbr></wbr></wbr></wbr></wbr></strong></p> <p><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)"></span><wbr style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px"><span style="font-size:14px; color:rgb(70,70,70); font-family:simsun; line-height:21px; background-color:rgb(240,231,180)">电话本UI框架（AddressBookUI.framework）是一个Objective-C标准程序接口，主要用来创建新联系人，编辑和选择 电话本中存在的联系人。它简化了在iPhone应用中显示联系人信息，并确保所有应用使用相同的程序接口，保证应用在不同平台的一致性。</span></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></p> <p><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px"></span><wbr style="color:rgb(70,70,70); font-family:simsun; font-size:14px"><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px"></span><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px; word-wrap:normal; word-break:normal"><strong>总结</strong></span><span style="color:rgb(70,70,70); font-family:simsun; font-size:14px">:</span></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <wbr><wbr><wbr><wbr><wbr><wbr>当我们要开发iPhone程序的时候，首先要现从上层入手，优先使用Objective-C封装后的库，也就是通过 UIKit.framework搭配Foundation.framework来进行开发，而当面对一些比较复杂的功能时，像是多媒体的处理或是绘图，再往下层去找寻相关的framwork开完成。</wbr></wbr></wbr></wbr></wbr></wbr></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <br></p> <p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> </p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> Cocoa框架是iOS应用程序的基础，了解Cocoa框架，对开发iOS应用有很大的帮助。</p> <h2 style="margin:0px; padding:0px; font-family:Arial"> <a target="_blank" name="t0" style="color:rgb(255,153,0)"></a><strong>1、Cocoa是什么？</strong> </h2> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> Cocoa是OS X和 iOS操作系统的程序的运行环境。</p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> 是什么因素使一个程序成为Cocoa程序呢？不是编程语言，因为在Cocoa开发中你可以使用各种语言；也不是开发工具，你可以在命令行上就可以创建Cocoa程序。Cocoa程序可以这么说，它是由一些对象组成，而这些对象的类最后都是继承于它们的根类 ：NSObject。而且它们都是基于Objective-C运行环境的。</p> <h3 style="margin:0px; padding:0px; font-family:Arial"> <a target="_blank" name="t1" style="color:rgb(255,153,0)"></a>1.1、Cocoa框架</h3> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> iOS中，Cocoa众多框架中最重要最基本的两个框架是：Foundation 和 UIKit。</p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> Foundation 和界面无关，也可以说和界面无关的类基本是Foundation框架的，和界面相关的是UIKit框架。<br></p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> 这两个框架在系统中处于的位置如图：</p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> <img src="http://img.my.csdn.net/uploads/201210/17/1350459010_4309.jpg" alt="" style="border:none; max-width:100%"></p> <h3 style="margin:0px; padding:0px; font-family:Arial"> <a target="_blank" name="t2" style="color:rgb(255,153,0)"></a>1.2、Foundation框架</h3> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> 好吧，那我们看看两个框架的类组织架构图，第一个先看Foundation的，三个图，包括了Foundation所以的类，图中灰色的是iOS不支持的，灰色部分是OS X系统的。<br></p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> <img src="http://img.my.csdn.net/uploads/201210/18/1350526881_2060.jpg" alt="" style="border:none; max-width:100%"><img src="http://img.my.csdn.net/uploads/201210/18/1350526897_3494.jpg" alt="" style="border:none; max-width:100%"></p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> <img src="http://img.my.csdn.net/uploads/201210/18/1350526913_6659.jpg" alt="" style="border:none; max-width:100%"><br></p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> 将上图Foundation框架中的类进行逻辑分类如下：<br></p> <ol style="font-family:Arial; font-size:14px"> <li><span style="font-weight:bold">值对象</span></li> <li><span style="font-weight:bold">集合</span></li> <li> <span style="font-weight:bold">操作系统服务 包括下面三个：</span><span style="font-weight:bold">文件系统和URL </span><strong>进程间通讯。</strong>这个范畴中的大部分类代表不同的系统端口、套接字、和名字服务器，对实现底层的IPC很有用。NSPipe代表一个BSD管道，即一种进程间的单向通讯通道。 <strong>线程和子任务。</strong>NSThread类使您可以创建多线程的程序，而各种锁（lock）类则为彼此竞争的线程在访问进程资源时提供各种控制机制。通过NSTask，您的程序可以分出 一个子进程来执行其它工作或进行进度监控。</li> <li><span style="font-weight:bold">通知</span></li> <li><span style="font-weight:bold">归档和序列化</span></li> <li><span style="font-weight:bold">表达式和条件判断</span></li> <li><span style="font-weight:bold">Objective-C语言服务</span></li> </ol> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <h3 style="margin:0px; padding:0px; font-family:Arial"> <a target="_blank" name="t3" style="color:rgb(255,153,0)"></a>1.3 UIKit框架</h3> <div style="font-family:Arial; font-size:14px">应用程序可以通过三种方式使用UIKit创建界面</div> <div style="font-family:Arial; font-size:14px"> <ol> <li> 在用户界面工具（interface Buidler）从对象库里 拖拽窗口，视图或者其他的对象使用。</li> <li> 用代码创建</li> <li> 通过继承UIView类或间接继承UIView类实现自定义用户界面</li> </ol> </div> <div style="font-family:Arial; font-size:14px"><br></div> <div style="font-family:Arial; font-size:14px"><span style="font-weight:bold">框架类组织架构图：</span></div> <div style="font-family:Arial; font-size:14px"><span style="font-weight:bold"><img src="http://img.my.csdn.net/uploads/201210/18/1350528267_1570.jpg" alt="" style="border:none; max-width:100%"><br></span></div> <div style="font-family:Arial; font-size:14px"><br></div> <div style="font-family:Arial; font-size:14px"><br></div> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> 在图中可以看出，responder 类是图中最大分支的根类，UIResponder为处理响应事件和响应链 定义了界面和默认行为。当用户用手指滚动列表或者在虚拟键盘上输入时，UIKit就生成时间传送给UIResponder响应链，直到链中有对象处理这个事件。相应的核心对象，比如：UIApplication ，UIWindow，UIView都直接或间接的从UIResponder继承。</p> <h2 style="margin:0px; padding:0px; font-family:Arial"> <a target="_blank" name="t4" style="color:rgb(255,153,0)"></a>2、Cocoa对象</h2> <h3 style="margin:0px; padding:0px; font-family:Arial"> <a target="_blank" name="t5" style="color:rgb(255,153,0)"></a>2.1 Objective-C是面向对象的语言</h3> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> Objective-C和Java C++一样，有封装，继承，多态，重用。但是它不像C++那样有重载操作法、模版和多继承，也没有Java的垃圾回收机制。<br></p> <h3 style="margin:0px; padding:0px; font-family:Arial"> <a target="_blank" name="t6" style="color:rgb(255,153,0)"></a>2.2Objective-C的优点</h3> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> Objective-C语言有C++ Java等面向对象的特点，那是远远不能体现它的优点的。Objective-C的优点是它是动态的。动态能力有三种：</p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> 动态类-运行时确定类的对象</p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> 动态绑定-运行时确定要调用的方法</p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> 动态加载--运行时为程序加载新的模块</p> <h3 style="margin:0px; padding:0px; font-family:Arial"> <a target="_blank" name="t7" style="color:rgb(255,153,0)"></a>2.3 动态能力相关的isa指针</h3> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> 每个Objective-C对象都有一个隐藏的数据结构，这个数据结构是Objective-C对象的第一个成员变量，它就是isa指针。这个指针指向哪呢？它指向一个类对象(class object 记住它是个对象，是占用内存空间的一个变量，这个对象在编译的时候编译器就生成了，专门来描述某个类的定义)，这个类对象包含了Objective-C对象的一些信息（为了区分两个对象，我把前面提到的对象叫Objective-C对象），包括Objective-C对象的方法调度表，实现了什么协议等等。这个包含信息就是Objective-C动态能力的根源了。</p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> 那我们看看isa指针类型的数据结构是什么样的？如果抛开NSObject对象的其他的成员数据和变量，NSObject可以看成这样：</p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <div class="dp-highlighter bg_cpp" style="font-family:Consolas,'Courier New',Courier,mono,serif; background-color:rgb(231,229,220); width:712.234375px; overflow:auto; padding-top:1px; margin:18px 0px!important"> <div class="bar" style="padding-left:45px"> <div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; background-color:rgb(248,248,248); border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108)"> <strong>[cpp]</strong><a target="_blank" href="http://blog.csdn.net/totogo2010/article/details/8081253#" class="ViewSource" title="view plain" style="color:rgb(160,160,160); text-decoration:none; background-color:inherit; border:none; padding:1px; margin:0px 10px 0px 0px; display:inline-block; width:16px; height:16px; text-indent:-2000px">view plain</a><span><a target="_blank" href="http://blog.csdn.net/totogo2010/article/details/8081253#" class="CopyToClipboard" title="copy" style="color:rgb(160,160,160); text-decoration:none; background-color:inherit; border:none; padding:1px; margin:0px 10px 0px 0px; display:inline-block; width:16px; height:16px; text-indent:-2000px">copy</a></span> <div style="position:absolute; left:372px; top:2921px; width:18px; height:18px; z-index:99"> </div> <span></span> </div> </div> <ol start="1" class="dp-cpp" style="padding:0px; border:none; list-style-position:initial; background-color:rgb(255,255,255); color:rgb(92,92,92); margin:0px 0px 1px 45px!important"> <li class="alt" style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit"><span style="margin:0px; padding:0px; border:none; background-color:inherit">@interfaceNSObject&lt;NSObject&gt;{</span></span> </li> <li style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; background-color:rgb(248,248,248); line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit">Classisa;</span> </li> <li class="alt" style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit">}</span> </li> </ol> </div> <span style="font-family:Arial; font-size:14px">不考虑@interface关键字在编译时的作用，可以把NSObject更接近C语言结构表示为：</span> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <div class="dp-highlighter bg_cpp" style="font-family:Consolas,'Courier New',Courier,mono,serif; background-color:rgb(231,229,220); width:712.234375px; overflow:auto; padding-top:1px; margin:18px 0px!important"> <div class="bar" style="padding-left:45px"> <div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; background-color:rgb(248,248,248); border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108)"> <strong>[cpp]</strong><a target="_blank" href="http://blog.csdn.net/totogo2010/article/details/8081253#" class="ViewSource" title="view plain" style="color:rgb(160,160,160); text-decoration:none; background-color:inherit; border:none; padding:1px; margin:0px 10px 0px 0px; display:inline-block; width:16px; height:16px; text-indent:-2000px">view plain</a><span><a target="_blank" href="http://blog.csdn.net/totogo2010/article/details/8081253#" class="CopyToClipboard" title="copy" style="color:rgb(160,160,160); text-decoration:none; background-color:inherit; border:none; padding:1px; margin:0px 10px 0px 0px; display:inline-block; width:16px; height:16px; text-indent:-2000px">copy</a></span> <div style="position:absolute; left:372px; top:3070px; width:18px; height:18px; z-index:99"> </div> <span></span> </div> </div> <ol start="1" class="dp-cpp" style="padding:0px; border:none; list-style-position:initial; background-color:rgb(255,255,255); color:rgb(92,92,92); margin:0px 0px 1px 45px!important"> <li class="alt" style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit"><span class="keyword" style="margin:0px; padding:0px; border:none; color:rgb(0,102,153); background-color:inherit; font-weight:bold">struct</span><span style="margin:0px; padding:0px; border:none; background-color:inherit">NSObject{</span></span> </li> <li style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; background-color:rgb(248,248,248); line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit">　　Classisa;</span> </li> <li class="alt" style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit">}</span> </li> </ol> </div> <span style="font-family:Arial; font-size:14px">Class是用typedef 定义的</span> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <div class="dp-highlighter bg_cpp" style="font-family:Consolas,'Courier New',Courier,mono,serif; background-color:rgb(231,229,220); width:712.234375px; overflow:auto; padding-top:1px; margin:18px 0px!important"> <div class="bar" style="padding-left:45px"> <div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; background-color:rgb(248,248,248); border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108)"> <strong>[cpp]</strong><a target="_blank" href="http://blog.csdn.net/totogo2010/article/details/8081253#" class="ViewSource" title="view plain" style="color:rgb(160,160,160); text-decoration:none; background-color:inherit; border:none; padding:1px; margin:0px 10px 0px 0px; display:inline-block; width:16px; height:16px; text-indent:-2000px">view plain</a><span><a target="_blank" href="http://blog.csdn.net/totogo2010/article/details/8081253#" class="CopyToClipboard" title="copy" style="color:rgb(160,160,160); text-decoration:none; background-color:inherit; border:none; padding:1px; margin:0px 10px 0px 0px; display:inline-block; width:16px; height:16px; text-indent:-2000px">copy</a></span> <div style="position:absolute; left:372px; top:3219px; width:18px; height:18px; z-index:99"> </div> <span></span> </div> </div> <ol start="1" class="dp-cpp" style="padding:0px; border:none; list-style-position:initial; background-color:rgb(255,255,255); color:rgb(92,92,92); margin:0px 0px 1px 45px!important"><li class="alt" style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit"><span class="keyword" style="margin:0px; padding:0px; border:none; color:rgb(0,102,153); background-color:inherit; font-weight:bold">typedef</span><span style="margin:0px; padding:0px; border:none; background-color:inherit"></span><span class="keyword" style="margin:0px; padding:0px; border:none; color:rgb(0,102,153); background-color:inherit; font-weight:bold">struct</span><span style="margin:0px; padding:0px; border:none; background-color:inherit">objc_class*Class;</span></span> </li></ol> </div> <span style="font-family:Arial; font-size:14px">那NSObject可以这么写了</span> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <div class="dp-highlighter bg_cpp" style="font-family:Consolas,'Courier New',Courier,mono,serif; background-color:rgb(231,229,220); width:712.234375px; overflow:auto; padding-top:1px; margin:18px 0px!important"> <div class="bar" style="padding-left:45px"> <div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; background-color:rgb(248,248,248); border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108)"> <strong>[cpp]</strong><a target="_blank" href="http://blog.csdn.net/totogo2010/article/details/8081253#" class="ViewSource" title="view plain" style="color:rgb(160,160,160); text-decoration:none; background-color:inherit; border:none; padding:1px; margin:0px 10px 0px 0px; display:inline-block; width:16px; height:16px; text-indent:-2000px">view plain</a><span><a target="_blank" href="http://blog.csdn.net/totogo2010/article/details/8081253#" class="CopyToClipboard" title="copy" style="color:rgb(160,160,160); text-decoration:none; background-color:inherit; border:none; padding:1px; margin:0px 10px 0px 0px; display:inline-block; width:16px; height:16px; text-indent:-2000px">copy</a></span> <div style="position:absolute; left:372px; top:3332px; width:18px; height:18px; z-index:99"> </div> <span></span> </div> </div> <ol start="1" class="dp-cpp" style="padding:0px; border:none; list-style-position:initial; background-color:rgb(255,255,255); color:rgb(92,92,92); margin:0px 0px 1px 45px!important"> <li class="alt" style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit"><span class="keyword" style="margin:0px; padding:0px; border:none; color:rgb(0,102,153); background-color:inherit; font-weight:bold">struct</span><span style="margin:0px; padding:0px; border:none; background-color:inherit">NSObject{</span></span> </li> <li style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; background-color:rgb(248,248,248); line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit">　　objc_class*isa</span> </li> <li class="alt" style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit">}</span> </li> </ol> </div> <span style="font-family:Arial; font-size:14px">那objc_class的结构是什么样的呢？大概是这样的：</span> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <div class="dp-highlighter bg_cpp" style="font-family:Consolas,'Courier New',Courier,mono,serif; background-color:rgb(231,229,220); width:712.234375px; overflow:auto; padding-top:1px; margin:18px 0px!important"> <div class="bar" style="padding-left:45px"> <div class="tools" style="padding:3px 8px 10px 10px; font-size:9px; line-height:normal; font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; color:silver; background-color:rgb(248,248,248); border-left-width:3px; border-left-style:solid; border-left-color:rgb(108,226,108)"> <strong>[cpp]</strong><a target="_blank" href="http://blog.csdn.net/totogo2010/article/details/8081253#" class="ViewSource" title="view plain" style="color:rgb(160,160,160); text-decoration:none; background-color:inherit; border:none; padding:1px; margin:0px 10px 0px 0px; display:inline-block; width:16px; height:16px; text-indent:-2000px">view plain</a><span><a target="_blank" href="http://blog.csdn.net/totogo2010/article/details/8081253#" class="CopyToClipboard" title="copy" style="color:rgb(160,160,160); text-decoration:none; background-color:inherit; border:none; padding:1px; margin:0px 10px 0px 0px; display:inline-block; width:16px; height:16px; text-indent:-2000px">copy</a></span> <div style="position:absolute; left:372px; top:3481px; width:18px; height:18px; z-index:99"> </div> <span></span> </div> </div> <ol start="1" class="dp-cpp" style="padding:0px; border:none; list-style-position:initial; background-color:rgb(255,255,255); color:rgb(92,92,92); margin:0px 0px 1px 45px!important"> <li class="alt" style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit"><span class="keyword" style="margin:0px; padding:0px; border:none; color:rgb(0,102,153); background-color:inherit; font-weight:bold">struct</span><span style="margin:0px; padding:0px; border:none; background-color:inherit">objc_class{</span></span> </li> <li style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; background-color:rgb(248,248,248); line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit">Classisa;</span> </li> <li class="alt" style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit"></span> </li> <li style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; background-color:rgb(248,248,248); line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit">Classsuper_class;</span> </li> <li class="alt" style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit"></span> </li> <li style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; background-color:rgb(248,248,248); line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit"><span class="keyword" style="margin:0px; padding:0px; border:none; color:rgb(0,102,153); background-color:inherit; font-weight:bold">const</span><span style="margin:0px; padding:0px; border:none; background-color:inherit"></span><span class="datatypes" style="margin:0px; padding:0px; border:none; color:rgb(46,139,87); background-color:inherit; font-weight:bold">char</span><span style="margin:0px; padding:0px; border:none; background-color:inherit">*name;</span></span> </li> <li class="alt" style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit"></span> </li> <li style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; background-color:rgb(248,248,248); line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit"><span class="datatypes" style="margin:0px; padding:0px; border:none; color:rgb(46,139,87); background-color:inherit; font-weight:bold">long</span><span style="margin:0px; padding:0px; border:none; background-color:inherit">version;</span></span> </li> <li class="alt" style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit"><span class="datatypes" style="margin:0px; padding:0px; border:none; color:rgb(46,139,87); background-color:inherit; font-weight:bold">long</span><span style="margin:0px; padding:0px; border:none; background-color:inherit">info;</span></span> </li> <li style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; background-color:rgb(248,248,248); line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit"></span> </li> <li class="alt" style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit"><span class="datatypes" style="margin:0px; padding:0px; border:none; color:rgb(46,139,87); background-color:inherit; font-weight:bold">long</span><span style="margin:0px; padding:0px; border:none; background-color:inherit">instance_size;</span></span> </li> <li style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; background-color:rgb(248,248,248); line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit"><span class="keyword" style="margin:0px; padding:0px; border:none; color:rgb(0,102,153); background-color:inherit; font-weight:bold">struct</span><span style="margin:0px; padding:0px; border:none; background-color:inherit">objc_ivar_list*ivars;</span></span> </li> <li class="alt" style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit"><span class="keyword" style="margin:0px; padding:0px; border:none; color:rgb(0,102,153); background-color:inherit; font-weight:bold">struct</span><span style="margin:0px; padding:0px; border:none; background-color:inherit">objc_method_list**methodLists;</span></span> </li> <li style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; background-color:rgb(248,248,248); line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit"></span> </li> <li class="alt" style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit"><span class="keyword" style="margin:0px; padding:0px; border:none; color:rgb(0,102,153); background-color:inherit; font-weight:bold">struct</span><span style="margin:0px; padding:0px; border:none; background-color:inherit">objc_cache*cache;</span></span> </li> <li style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; background-color:rgb(248,248,248); line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit"><span class="keyword" style="margin:0px; padding:0px; border:none; color:rgb(0,102,153); background-color:inherit; font-weight:bold">struct</span><span style="margin:0px; padding:0px; border:none; background-color:inherit">objc_protocol_list*protocols;</span></span> </li> <li class="alt" style="border-style:none none none solid; border-left-width:3px; border-left-color:rgb(108,226,108); list-style:decimal-leading-zero outside; color:inherit; line-height:18px; margin:0px!important; padding:0px 3px 0px 10px!important"> <span style="margin:0px; padding:0px; border:none; color:black; background-color:inherit">}</span> </li> </ol> </div> <span style="font-family:Arial; font-size:14px">这里会看到，在这个结构体里还有一个isa指针，又是一重指向，是不是有种到了盗梦空间的感觉。不用紧张，take easy，不会有那么多层次的，这里的isa指针指向的是元类对象(metaclass object)，带有元字，证明快到头了。那元对象有啥用呢？它用来存储的关于类的版本，名字，类方法等信息。所有的元类对象(metaclass object)都指向 NSObject的元类对象，到头还是NSObject。一共三次：类对象-&gt;元类对象-&gt;NSObject元类对象。</span> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> 为了得到整个类组织架构的信息，objc_class结构里定义了第二个成员变量Class super_class，它指向父类的类对象。说了这么多，可能关系缕不清楚，有道是一张图胜过千言万语</p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> <img src="http://img.my.csdn.net/uploads/201210/21/1350831500_2327.jpg" alt="" style="border:none; max-width:100%"><br></p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> 图中可以看出，D3继承D2,D2继承D1,D1最终继承NSObject。下图从D3的一个对象开始，排列出D3 D2 D1 NSObject 类对象，元类对象等关系。</p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> <img src="http://img.my.csdn.net/uploads/201210/21/1350831599_3230.png" alt="" style="border:none; max-width:100%"><br></p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> 图中的箭头都是指针的指向。</p> <h3 style="margin:0px; padding:0px; font-family:Arial"> <a target="_blank" name="t8" style="color:rgb(255,153,0)"></a>2.4 根类 NSObject</h3> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> NSObject是大部分Objective-C类的根类，它没有父类。其它类继承NSObject，访问Objective-C运行时系统的基本接口，这样其他类的实例可以获得运行时的能力。<br></p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> <img src="http://img.my.csdn.net/uploads/201210/22/1350871031_1713.jpg" alt="" style="border:none; max-width:100%"><br></p> <h4 style="margin:0px; padding:0px; font-family:Arial; font-size:14px"> <a target="_blank" name="t9" style="color:rgb(255,153,0)"></a><strong>2.4.1 根类和根类协议</strong> </h4> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> NSObject不但是个类名，NSObject也是个协议的名称，<a target="_blank" href="http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Protocols/NSObject_Protocol/Reference/NSObject.html" style="color:rgb(255,153,0); text-decoration:none">参考NSObject协议</a>， NSObject协议指定了根类必须实现的接口。</p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <h4 style="margin:0px; padding:0px; font-family:Arial; font-size:14px"> <a target="_blank" name="t10" style="color:rgb(255,153,0)"></a><strong>2.4.2 根类的主要方法：</strong> </h4> <h5 style="font-family:Arial"> <a target="_blank" name="t11" style="color:rgb(255,153,0)"></a> <ul><li> 分配、初始化、和复制：</li></ul> </h5> <span style="font-family:Arial; font-size:14px">alloc和allocWithZone:方法用于从某内存区域中分配一个对象内存，并使对象指向其运行时的类定义。</span><br style="font-family:Arial; font-size:14px"><span style="font-family:Arial; font-size:14px">init方法是对象初始化。</span><br style="font-family:Arial; font-size:14px"><span style="font-family:Arial; font-size:14px">new是一个将简单的内存分配和初始化结合起来的方法。</span><br style="font-family:Arial; font-size:14px"><span style="font-family:Arial; font-size:14px">copy和copyWithZone:</span> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <h5 style="font-family:Arial"> <a target="_blank" name="t12" style="color:rgb(255,153,0)"></a> <ul><li>对象的保持和清理：</li></ul> </h5> <span style="font-family:Arial; font-size:14px">retain方法增加对象的保持次数。</span><br style="font-family:Arial; font-size:14px"><span style="font-family:Arial; font-size:14px">release方法减少对象的保持次数。</span><br style="font-family:Arial; font-size:14px"><span style="font-family:Arial; font-size:14px">autorelease方法也是减少对象的保持次数，但是以推迟的方式。</span><br style="font-family:Arial; font-size:14px"><span style="font-family:Arial; font-size:14px">retainCount方法返回对当前的保持次数。</span><br style="font-family:Arial; font-size:14px"><span style="font-family:Arial; font-size:14px">dealloc方法由需要释放对象的实例变量以及释放动态分配的内存的类实现。</span><br style="font-family:Arial; font-size:14px"><h5 style="font-family:Arial"> <a target="_blank" name="t13" style="color:rgb(255,153,0)"></a> <ul><li>内省和比较</li></ul> </h5> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> NSObjec有很多方法可以查询对象的运行时信息。这些内省方法有助于找出对象在类层次中的位置，确定对象是否实现特定的方法，以及测试对象是否遵循某种协议。下面是部分方法<br> superclass和class方法（实现为类和实例方法）分别以Class对象的形式返回接收者的父类和类。<br> 您可以通过isKindOfClass:和isMemberOfClass:方法来确定对象属于哪个类。后者用于测试接收者是否为指定类的实例。isSubclassOfClass:类方法则用于测试类的继承性。<br> respondsToSelector:方法用于测试接收者是否实现由选择器参数标识的方法。instancesRespondToSelector:类方法则用于测试给定类的实例是否实现指定的方法。<br> conformsToProtocol:方法用于测试接收者（对象或类）是否遵循给定的协议。<br> isEqual:和hash方法用于对象的比较。<br> description方法允许对象返回一个内容描述字符串；这个方法的输出经常用于调试（“print object”命令），以及在格式化字符串中和“%@”指示符一起表示对象。<br></p> <h5 style="font-family:Arial"> <a target="_blank" name="t14" style="color:rgb(255,153,0)"></a> <ul><li>对象的编码和解码</li></ul> </h5> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> 下面的方法和对象的编解码（作为归档过程的一部分）有关：<br> encodeWithCoder:和initWithCoder:是NSCoding协议仅有的方法。前者使对象可以对其实例变量进行编码，后者则使对象可以根据解码过的实例变量对自身进行初始化。<br> NSObject类中声明了一些于对象编码有关的方法：classForCoder:、replacementObjectForCoder:、和awakeAfterUsingCoder:。<br></p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <h5 style="font-family:Arial"> <a target="_blank" name="t15" style="color:rgb(255,153,0)"></a> <ul><li>消息的转发</li></ul> </h5> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> <strong></strong>forwardInvocation:允许一个对象将消息转发给另一个对象。<br></p> <h5 style="font-family:Arial"> <a target="_blank" name="t16" style="color:rgb(255,153,0)"></a> <ul><li>消息的派发</li></ul> </h5> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> 在performSelector开头的一些方法允许你延迟后派发指定消息，而且可以将消息（同步或异步的消息）从辅助线程派发到主线程。<br></p> <h3 style="margin:0px; padding:0px; font-family:Arial"> <a target="_blank" name="t17" style="color:rgb(255,153,0)"></a>2.5 Cocoa对象生命周期</h3> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> 对象的四种内存管理方式，如下图所示</p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <ul style="font-family:Arial; font-size:14px"><li><strong>对象的生命周期—简化视图</strong></li></ul> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> <img src="http://img.my.csdn.net/uploads/201210/22/1350871223_8473.gif" alt="" style="border:none; max-width:100%"><br></p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <ul style="font-family:Arial; font-size:14px"><li><span style="font-family:'Lucida Grande',Geneva,Helvetica,Arial,sans-serif"><strong>保持接收到的对象</strong></span></li></ul> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> <img src="http://img.my.csdn.net/uploads/201210/22/1350871326_3857.gif" alt="" style="border:none; max-width:100%"><br></p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <ul style="font-family:Arial; font-size:14px"><li><span style="font-family:'Lucida Grande',Geneva,Helvetica,Arial,sans-serif"><strong>拷贝接收到的对象</strong></span></li></ul> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> <img src="http://img.my.csdn.net/uploads/201210/22/1350871361_2570.gif" alt="" style="border:none; max-width:100%"><br></p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <ul style="font-family:Arial; font-size:14px"><li><span style="font-family:'Lucida Grande',Geneva,Helvetica,Arial,sans-serif"><strong>自动释放池</strong></span></li></ul> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> <img src="http://img.my.csdn.net/uploads/201210/22/1350871395_7054.gif" alt="" style="border:none; max-width:100%"><br></p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> <br></p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> <br></p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> 参考：</p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> <span style="color:rgb(75,75,75); font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; font-size:13px; line-height:19px">1、http://algorithm.com.au/downloads/talks/objective-c-internals/objective-c-internals.pdf</span><br></p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> <span style="color:rgb(75,75,75); font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; font-size:13px; line-height:19px">2、http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/CocoaFundamentals/Introduction/Introduction.html</span></p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> <span style="color:rgb(75,75,75); font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; font-size:13px; line-height:19px">3、http://www.cnblogs.com/csutanyu/archive/2011/12/12/Objective-C_memory_layout.html</span></p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> <span style="color:rgb(75,75,75); font-family:Verdana,Geneva,Arial,Helvetica,sans-serif; font-size:13px; line-height:19px">4 <span style="color:rgb(51,102,204); font-family:'Lucida Grande','Lucida Sans Unicode',Helvetica,Arial,Verdana,sans-serif">http://blog.csdn.net/iukey/article/category/1168345</span></span></p> <p style="margin-top:0px; margin-bottom:0px; padding-top:0px; padding-bottom:0px; font-family:Arial; font-size:14px"> </p> <p style="margin:10px auto; padding-top:0px; padding-bottom:0px; font-family:verdana,宋体,Arial; font-size:13px; line-height:24px"> <span style="color:rgb(255,0,0)">容芳志 (<a target="_blank" href="http://blog.csdn.net/totogo2010" style="color:rgb(255,153,0); text-decoration:none; margin:0px; padding:0px; border-bottom-width:1px; border-bottom-style:dotted; border-bottom-color:rgb(51,51,51)">http://blog.csdn.net/totogo2010</a>)</span></p> <p style="margin:10px auto; padding-top:0px; padding-bottom:0px; font-family:verdana,宋体,Arial; font-size:13px; line-height:24px"> <span style="color:rgb(255,0,0)">本文遵循“<a target="_blank" href="http://creativecommons.org/licenses/by-nc-sa/2.5/cn/" style="color:rgb(255,153,0); text-decoration:none; margin:0px; padding:0px; border-bottom-width:1px; border-bottom-style:dotted; border-bottom-color:rgb(51,51,51)">署名-非商业用途-保持一致</a>”创作公用协议</span></p> <br><p style="font-size:14px; margin-top:0px; margin-bottom:5px; padding-top:0px; padding-bottom:0px; border:0px; list-style:none; word-wrap:normal; word-break:normal; line-height:21px; color:rgb(70,70,70); font-family:simsun"> <br></p> </wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr></wbr>