正在删除通知

我有一个模型对象和一个窗口控制器。我希望他们能够通过通知进行沟通。我在应用程序代理的 -applicationDidFinishLaunching: 方法。我在加载窗口控制器的窗口后添加观察者,如下所示:

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
    WordSetWindowController* windowController = [[WordSetWindowController alloc] initWithWindowNibName:@"WordSetWindowController"];

    model = [[WordSetModel alloc] init];

    NSWindow*   window = windowController.window;

    [[NSNotificationCenter defaultCenter] addObserver:windowController
                                             selector:@selector(handleNotification:)
                                                 name:kNotification_GeneratingPairs
                                               object:model];

    [[NSNotificationCenter defaultCenter] addObserver:windowController
                                             selector:@selector(handleNotification:)
                                                 name:kNotification_ProcessingPairs
                                               object:model];

    [[NSNotificationCenter defaultCenter] addObserver:windowController
                                             selector:@selector(handleNotification:)
                                                 name:kNotification_UpdatePairs
                                               object:model];

    [[NSNotificationCenter defaultCenter] addObserver:windowController
                                             selector:@selector(handleNotification:)
                                                 name:kNotification_Complete
                                               object:model];

    [model initiateSearch];
}

这个 -iniateSearch 方法启动一些线程以在后台执行一些处理器密集型计算。我希望这些线程发送通知,以便在处理过程中更新UI。看起来是这样的:

- (void)initiateSearch;
{
    [[NSNotificationCenter defaultCenter] postNotificationName:kNotification_GeneratingPairs
                                                        object:self];

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        // ... do the first part of the calculations ...

        // Notify the UI to update
        self->state = SearchState_ProcessingPairs;
        dispatch_async(dispatch_get_main_queue(), ^{
            [[NSNotificationCenter defaultCenter] postNotificationName:kNotification_ProcessingPairs
                                                                object:self];
        });

        // ... Do some more calculations ...

        // Notify the UI that we're done
        self->state = SearchState_Idle;
        dispatch_sync(dispatch_get_main_queue(), ^{
            [[NSNotificationCenter defaultCenter] postNotificationName:kNotification_Complete
                                                                object:self];
        });

    });
}

第一个通知工作正常,但在 dispatch_async() 调用会导致调用通知处理程序。我试过打电话 -postNotificationName:: dispatch_async(dispatch_get_main_queue(),...) 通过打电话 -performSelectorOnMainThread::: )两者都没有任何效果。

出于好奇,我通过 NSTimer 等了5秒钟 调度异步() 结束时呼叫 -initiateSearch: 并且发现即使所有这些都发生在主UI线程上,它也不会启动通知处理程序。如果我只是打电话 postNotification::: 紧接着 调度异步() 调用返回,但工作正常。

由此,我得出结论,尽管我的代码从未调用-removeObserver:。为什么会发生这种事,我怎样才能不让它发生,或者我可以把我的电话转到哪里 -addObserver 所以他们不受影响?