ios - 在主线程上发布 NSNotification

Question

我发现下面的代码片段允许 NSNotification 从任何后台线程发布到主线程。我想知道这是否是一种安全且可接受的做法？

dispatch_async(dispatch_get_main_queue(),^{
    [[NSNotificationCenter defaultCenter] postNotificationName:@"ImageRetrieved" 
                                                        object:nil 
                                                      userInfo:imageDict];
});

Answer 1

是的，你可以。

通常，您希望在 main 上发送 NSNotifications，尤其是当它们触发 UI 事件(例如关闭模式登录对话框)时。

Delivering Notifications To Particular Threads

Regular notification centers deliver notifications on the thread in which the notification was posted. Distributed notification centers deliver notifications on the main thread. At times, you may require notifications to be delivered on a particular thread that is determined by you instead of the notification center. For example, if an object running in a background thread is listening for notifications from the user interface, such as a window closing, you would like to receive the notifications in the background thread instead of the main thread. In these cases, you must capture the notifications as they are delivered on the default thread and redirect them to the appropriate thread.