Objective c 使用调度异步、can'；是否在同一控制器上触发两个函数调用？

我的AppDelegate中有以下方法。我找不到一种方法来更新updateView上的标签并通过ASIHTTPRequest执行上载。在下面的代码中，它将执行上载（startUpload），但不更新标签（updateLabel）。如果我注释掉对startUpload的调用，它将更新标签。我还尝试在uploadViewController中创建一个调度队列，结果类似，我只能使用这两种方法中的一种

- (void) showProgressView:(NSString *)filePath {
    NSView *view = [uploadViewController view];
    dispatch_queue_t queue = dispatch_get_global_queue(0,0);
    dispatch_async(queue, ^{
        // assigns the upload view to the root NSPanel
        [box setContentView:view];
    });
    dispatch_async(queue, ^{
        // starts the upload using ASIHTTPRequest
        [uploadViewController startUpload:filePath];
    });
    dispatch_async(queue, ^{
        // updates a label in the upload view
        [uploadViewController updateLabel];
    });
}

在UploadViewController中：

-(void)startUpload:(NSString *)filePath {
    HandZipper *handZipper = [HandZipper alloc];
    zipPath = [handZipper compressHands:(filePath):(processStatus)];   

    ASIFormDataRequest *request = [[[ASIFormDataRequest alloc] initWithURL:[NSURL URLWithString:@"http://allseeing-i.com/ignore"]] autorelease];

    [request setRequestMethod:@"PUT"];
    [request setPostBodyFilePath:zipPath];
    [request setShouldStreamPostDataFromDisk:YES];
    [request setDelegate:self];
    [request setUploadProgressDelegate:progressIndicator];
    [request setDidFinishSelector:@selector(postFinished:)];
    [request setDidFailSelector:@selector(postFailed:)];
    [request startSynchronous]; 

}

---

您应该始终更新主线程上的UI元素。如果您知道将从主线程调用

showProgressView:

，则从

[box setContentView:view]周围删除dispatch\u async和
[uploadViewController updateLabel]showProgressView:
，则只需使用
dispatch\u get\u main\u queue（void）
而不是
queue