Swift - 多线程实现方式(1) - Thread
1,Swift继续使用Object-C原有的一套线程,包括三种多线程编程技术:
4,线程同步
输出结果:
原文出自:www.hangge.com 转载请保留原文链接:http://www.hangge.com/blog/cache/detail_743.html
(1)Thread
(2)Cocoa Operation(Operation和OperationQueue)
(3)Grand Central Dispath(GCD)
2,本文着重介绍Thread
Tread在三种多线程技术中是最轻量级的,但需要自己管理线程的生命周期和线程同步。线程同步对数据的加锁会有一定的系统开销。(本文代码已全部更新至Swift3)
3,Thread的两种创建方式
(1)直接创建线程并且自动运行线程
(2)先创建一个线程对象,然后手动运行线程,在运行线程操作之前可以设置线程的优先级等线程信息。
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import UIKit
class ViewController : UIViewController {
override func viewDidLoad()
{
super .viewDidLoad()
//方式1:使用类方法
Thread .detachNewThreadSelector(#selector( ViewController .downloadImage),
toTarget: self ,
with: nil )
//方式2:实例方法-便利构造器
let myThread
= Thread (target: self ,
selector:
#selector( ViewController .downloadImage),
object: nil )
myThread.start()
}
//定义一个下载图片的方法,线程调用
func downloadImage(){
let data
= try! Data (contentsOf: URL (string:
imageUrl)!)
print (data.count)
}
override func didReceiveMemoryWarning()
{
super .didReceiveMemoryWarning()
}
}
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4,线程同步
线程同步方法通过锁来实现,每个线程都只用一个锁,这个锁与一个特定的线程关联。下面演示两个线程之间的同步。
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import UIKit
class ViewController : UIViewController {
//定义两个线程
var thread1: Thread ?
var thread2: Thread ?
//定义两个线程条件,用于锁住线程
let condition1
= NSCondition ()
let condition2
= NSCondition ()
override func viewDidLoad()
{
super .viewDidLoad()
thread2
= Thread (target: self ,
selector: #selector( ViewController .method2),
object: nil )
thread1
= Thread (target: self ,
selector: #selector( ViewController .method1),
object: nil )
thread1?.start()
}
//定义两方法,用于两个线程调用
func method1(sender: AnyObject ){
for i in 0
..< 10 {
print ( "Thread
1 running \(i)" )
sleep(1)
if i
== 2 {
thread2?.start() //启动线程2
//本线程(thread1)锁定
condition1.lock()
condition1.wait()
condition1.unlock()
}
}
print ( "Thread
1 over" )
//线程2**
condition2.signal()
}
//方法2
func method2(sender: AnyObject ){
for i in 0
..< 10 {
print ( "Thread
2 running \(i)" )
sleep(1)
if i
== 2 {
//线程1**
condition1.signal()
//本线程(thread2)锁定
condition2.lock()
condition2.wait()
condition2.unlock()
}
}
print ( "Thread
2 over" )
}
override func didReceiveMemoryWarning()
{
super .didReceiveMemoryWarning()
}
}
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原文出自:www.hangge.com 转载请保留原文链接:http://www.hangge.com/blog/cache/detail_743.html