XCode在发布图像后阻止UIWebView闪烁的白色屏幕

Question

我对XCode相当陌生 - 我正在设计一个带有单个视图的应用程序，该视图只显示加载我的jQuery移动网站的UIWebView。

我有Default.png和[email protected]文件启动图像的地方。当我在测试设备或模拟器上运行应用程序时，它会显示我的启动图像，然后在UIWebView加载第一页时闪烁白色屏幕。

我知道我可以更改背景颜色和不透明度，所以它会闪烁不同于白色的颜色，但我想完全防止闪光。我希望应用程序启动，显示启动图像，并在第一页完全加载之前不显示UIWebView。帮帮我？

Answer 1

@安德烈亚斯Volz的（和其他人想知道如何解决了白色的“闪光”的问题）

首先，添加name-of-loading-image.png和[email protected]文件到您的Xcode项目。常规形象应该是320×460，和@2x形象应该是640×920

然后，在我的ViewController.h文件我加了这些属性：

@property (nonatomic, retain) UIWebView *webView; 
@property(nonatomic, strong) UIImageView *loadingImageView; 
@end 

然后在我的ViewController.m文件中添加此：

#import "ViewController.h" 

@interface ViewController() 

@end 

@implementation ViewController; 

@synthesize webView; 
@synthesize loadingImageView; 

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 


    //**************** Set website URL for UIWebView 
    [webView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.example.com"] cachePolicy:NSURLCacheStorageAllowed timeoutInterval:20.0]]; 


    //**************** Add Static loading image to prevent white "flash" ****************/ 
    UIImage *loadingImage = [UIImage imageNamed:@"name-of-loading-image.png"]; 
    loadingImageView = [[UIImageView alloc] initWithImage:loadingImage]; 
     loadingImageView.animationImages = [NSArray arrayWithObjects: 
              [UIImage imageNamed:@"name-of-loading-image.png"], 
              nil]; 
    [self.view addSubview:loadingImageView]; 

} 

- (void)webViewDidFinishLoad:(UIWebView *)webView { 

    // Remove loading image from view 
    [loadingImageView removeFromSuperview]; 

} 

Answer 2

要知道您的webView何时完成加载，您必须实现UIWebViewDelegate协议。

在你的viewController的.h文件中：

@interface viewController : UIViewController <UIWebViewDelegate> 
{ 
    UIWebView *webView; 
} 
@end 

在你的viewController的.m文件

然后，添加这个方法：

- (void)webViewDidFinishLoad:(UIWebView *)webView { 

    NSLog(@"content loading finished"); 
    // Display your webView 
    [self.view addSubview:webView]; 

} 

可以使用-viewDidLoad方法在你的viewController的.M到继续显示您的启动图像。你也可以开始内容加载的网页视图：

- (void)viewDidLoad { 
    [super viewDidLoad]; 

    // continue to display launch image 
    UIImage *launchImage = [[UIImage alloc] initWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"launchImage.png" ofType:nil ]]; 
    UIImageView *launchImageView = [[[UIImageView alloc] initWithImage:launchImage] autorelease]; 
    [self.view addSubview:launchImageView]; 

    // now setup the base view for the webView controller 
    UIView *contentView = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]]; 
    contentView.backgroundColor = [UIColor blueColor]; 

    // for rotation 
    contentView.autoresizingMask = (UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight); 
    self.view = contentView; 

    //create a frame to size and place the web view 
    CGRect webFrame = [[UIScreen mainScreen] applicationFrame]; 
    UIWebView *aWebView = [[UIWebView alloc] initWithFrame:webFrame]; 
    self.webView = aWebView; 

    //aWebView.scalesPageToFit = YES; 
    aWebView.autoresizesSubviews = YES; 
    aWebView.autoresizingMask=(UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth); 

    //set the web view delegates for the web view to be itself 
    [aWebView setDelegate:self]; 

    //determine the path the to the index.html file in the Resources directory 
    NSURL *url = [[NSBundle mainBundle] URLForResource:@"index" withExtension:@"html"]; 
    NSURLRequest *requestObj = [NSURLRequest requestWithURL:url]; 
    [aWebView loadRequest:requestObj]; 
}