ASIHTTPRequest 异步下载

- (IBAction)fetchThreeImages:(id)sender
{    
    //清空三个imageview
    [imageView1 setImage:nil];
    [imageView2 setImage:nil];
    [imageView3 setImage:nil];
    
    //初始化一个网络连接对象
    if (!networkQueue) {
        networkQueue = [[ASINetworkQueue alloc] init];    
    }
    failed = NO;
    [networkQueue reset];//重设网络连接对象，如果代理灯一些设置
    [networkQueue setDownloadProgressDelegate: test];//设置下载进度条的代理
    [networkQueue setRequestDidFinishSelector: @selector(imageFetchComplete:)];//设置下载完成后，所调用的方法
    [networkQueue setRequestDidFailSelector: @selector(imageFetchFailed:)];//设置下载失败调用的方法
    [networkQueue setShowAccurateProgress: YES];//是否显示详细的进度，就是是否有一个连续的进入显示
    [networkQueue setDelegate:self];//设置网络连接对象的代理
    
    ASIHTTPRequest *request;
    //设置下载的地址
    request = [ASIHTTPRequest requestWithURL:[NSURL URLWithString:@"http://allseeing-i.com/ASIHTTPRequest/tests/images/small-image.jpg"]];
    //设置下载的文件的保持路径
    [request setDownloadDestinationPath:[[NSHomeDirectory() stringByAppendingPathComponent:@"Documents"] stringByAppendingPathComponent:@"1.png"]];
    //设置用于下载显示的进入的进度条
    [request setDownloadProgressDelegate: imageProgressIndicator1];
    [request setUserInfo:[NSDictionary dictionaryWithObject:@"request1" forKey:@"name"]];
    //添加这个下载
    [networkQueue addOperation:request];
    
    //同上
    request = [ASIHTTPRequest initWithURL:[NSURL URLWithString:@"http://allseeing-i.com/ASIHTTPRequest/tests/images/medium-image.jpg"]];
    [request setDownloadDestinationPath:[[NSHomeDirectory() stringByAppendingPathComponent:@"Documents"] stringByAppendingPathComponent:@"2.png"]];
    [request setDownloadProgressDelegate:imageProgressIndicator2];
    [request setUserInfo:[NSDictionary dictionaryWithObject:@"request2" forKey:@"name"]];
    [networkQueue addOperation:request];
    
    //同上
    request = [ASIHTTPRequest initWithURL:[NSURL URLWithString:@"http://allseeing-i.com/ASIHTTPRequest/tests/images/large-image.jpg"]];
    [request setDownloadDestinationPath:[[NSHomeDirectory() stringByAppendingPathComponent:@"Documents"] stringByAppendingPathComponent:@"3.png"]];
    [request setDownloadProgressDelegate:imageProgressIndicator3];
    [request setUserInfo:[NSDictionary dictionaryWithObject:@"request3" forKey:@"name"]];
    [networkQueue addOperation:request];
    
    //开始下载
    [networkQueue go];
}