ios - AFNetworking 2.0 和背景图片

Question

我正在尝试使用 AFNetworking 加载将在我的应用程序背景中显示的图像。当 viewDidLoad 调用加载图像时，问题就来了，AFNetworking 没有完成加载数据，所以它不显示。

这是我的代码。

AFNetworking:

AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
operation.responseSerializer = [AFJSONResponseSerializer serializer];

[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {

    // 3
    NSDictionary *user = (NSDictionary *)responseObject;

    NSString *backurlJSON=[user valueForKeyPath:@"back_url"][0];
    NSLog(@"Background from Start: %@",backurlJSON);

    if(![backurlJSON isEqualToString:@""]){

        NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"http://www.mydomain.com/images/%@", backurlJSON]];
         NSData *data = [[NSData alloc]initWithContentsOfURL:url ];
         imgBack = [[UIImage alloc]initWithData:data ];

        backgroundView = [[UIImageView alloc] initWithImage: imgBack];

所以在 viewDidLoad 中，我有 subview UIImageView 加载图像，以防万一没有要加载的图像，我想用来自的图像覆盖AFNetworking。

ViewDidLoad:

background = [UIImage imageNamed: @"2.png"];
backgroundView = [[UIImageView alloc] initWithImage: background];
backgroundView.frame = CGRectMake(-10, -10, 340, 588);
backgroundView.contentMode = UIViewContentModeScaleAspectFill;
[self.view addSubview:backgroundView];

知道怎么做吗？

Answer 1

使用您的代码，您正在使用 AFNetworking 下载带有“back_url”的 JSON 文件，然后您在主线程中下载图像，而不是此代码:

if(![backurlJSON isEqualToString:@""]){

    NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"http://www.mydomain.com/images/%@", backurlJSON]];
    NSData *data = [[NSData alloc]initWithContentsOfURL:url ];
    imgBack = [[UIImage alloc]initWithData:data ];

    backgroundView = [[UIImageView alloc] initWithImage: imgBack];
}

你可以使用类似的东西:

    NSString *backurlJSON=[user valueForKeyPath:@"back_url"][0];
    NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"http://www.mydomain.com/images/%@", backurlJSON]];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];


    AFHTTPRequestOperation *postOperation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
    postOperation.responseSerializer = [AFImageResponseSerializer serializer];
    [postOperation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
        backgroundView.image = responseObject;

    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        NSLog(@"Image error: %@", error);
    }];