IOS中UIWebView加载Loading的实现方法

//创建UIWebView
WebView = [[UIWebView alloc] initWithFrame:CGRectMake(0, 44, 320, 400)];
[WebView setUserInteractionEnabled:NO];
[WebView setBackgroundColor:[UIColor clearColor]];
[WebView setDelegate:self];
[WebView setOpaque:NO];//使网页透明
NSString *path = @"http://www.baidu.com";
NSURL *url = [NSURL URLWithString:path];
[WebView loadRequest:[NSURLRequest requestWithURL:url]];
//创建UIActivityIndicatorView背底半透明View  
UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 480)];
[view setTag:103];
[view setBackgroundColor:[UIColor blackColor]];
[view setAlpha:0.8];
[self.view addSubview:view];
activityIndicator = [[UIActivityIndicatorView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, 32.0f, 32.0f)];
[activityIndicator setCenter:view.center];
[activityIndicator setActivityIndicatorViewStyle:UIActivityIndicatorViewStyleWhite];
[view addSubview:activityIndicator];
[self.view addSubview:WebView];
[view release];
[WebView release];
//开始加载数据
- (void)webViewDidStartLoad:(UIWebView *)webView {  
      [activityIndicator startAnimating];       
}
//数据加载完
- (void)webViewDidFinishLoad:(UIWebView *)webView {
     [activityIndicator stopAnimating];  
     UIView *view = (UIView *)[self.view viewWithTag:103];
     [view removeFromSuperview];
}

//加载网页动画
- (void)webViewDidStartLoad:(UIWebView *)webView{
    if (myAlert==nil){      
       myAlert = [[UIAlertView alloc] initWithTitle:nil
                                                              message: @"读取中..."
                                                                delegate: self
                                                 cancelButtonTitle: nil
                                                 otherButtonTitles: nil];
     UIActivityIndicatorView *activityView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite];
     activityView.frame = CGRectMake(120.f, 48.0f, 38.0f, 38.0f);
     [myAlert addSubview:activityView];
     [activityView startAnimating];
     [myAlert show];
     }
}
- (void)webViewDidFinishLoad:(UIWebView *)webView{
      [myAlert dismissWithClickedButtonIndex:0 animated:YES];
}

NSData *gif = [NSData dataWithContentsOfFile: [[NSBundle mainBundle] pathForResource:@"1" ofType:@"gif"]]; 
// view生成 
UIWebView *webView = [[UIWebView alloc] initWithFrame:CGRectMake(100, 100, 70, 30)]; 
webView.userInteractionEnabled = NO;//用户不可交互 
[webView loadData:gif MIMEType:@"image/gif" textEncodingName:nil baseURL:nil]; 
[self.view addSubview:webView];