小编Ste*_*fan的帖子

AFHTTPSessionManager *manager = [AFHTTPSessionManager manager];
    manager.requestSerializer = [AFJSONRequestSerializer serializer];
    manager.responseSerializer = [AFJSONResponseSerializer serializer];
    [manager.requestSerializer setValue:[NSString stringWithFormat:@"Bearer %@", [[NSUserDefaults standardUserDefaults] objectForKey:TOKEN]] forHTTPHeaderField:@"Authorization"];
    [manager.requestSerializer setValue:@"application/json" forHTTPHeaderField:@"Accept"];
    [manager.requestSerializer setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];
    [manager POST:@"http:xxxxx" parameters:parameters constructingBodyWithBlock:^(id<AFMultipartFormData> formData) {
        [formData appendPartWithFileData:profileImage name:@"file" fileName:@"profileImage.jpg" mimeType:@"image/jpeg"];
    } success:^(NSURLSessionTask *task, id responseObject) {
        completionHandler(responseObject);
    } failure:^(NSURLSessionTask *operation, NSError *error) {
        NSData *errorData = error.userInfo[AFNetworkingOperationFailingURLResponseDataErrorKey];
        NSDictionary *serializedData = [NSJSONSerialization JSONObjectWithData: errorData options:kNilOptions error:nil];
        errorHandler(serializedData);
    }];

此方法工作正常,但constructingBodyWithBlock已弃用.如何优化代码以符合AFNetworking 3.0标准？

我很清楚 dispatch_async 队列正在执行什么，但我不清楚 dispatch_sync 的目的是什么。例如：这有什么区别：

NSLog(@"A");
NSLog(@"B");

和这个：

dispatch_sync(dispatch_get_main_queue(), ^ {
NSLog(@"A");
    });
NSLog(@"B");

据我所知，两种方式的输出都是 A 然后是 B。因为同步是按照写入的顺序执行的。谢谢。

我为iOS9编写的代码非常好用:

UIAlertController* alert = [UIAlertController alertControllerWithTitle:@"Select source"
                                                                   message:nil
                                                            preferredStyle:UIAlertControllerStyleActionSheet];
    alert.view.backgroundColor = DARK_BLUE;
    alert.view.tintColor = NEON_GREEN;
    UIView *subview = alert.view.subviews.firstObject;
    UIView *alertContentView = subview.subviews.firstObject;
    alertContentView.backgroundColor = DARK_BLUE;
    alertContentView.layer.cornerRadius = 10;

我的观点是UIAlertController继承UIViewController,并UIViewController具有UIView可以改变的属性.这是有效的.现在,继承UIViewController的视图有自己的子视图,contentView显示为Alert.我可以在子视图数组中以firstObject的形式访问它.现在,为什么发送背景颜色的消息不再起作用？有谁知道一些新的解决方案？