ios - didBecomeActive 发布通知，我的 View Controller 从未听到它

Question

应用委托(delegate):

- (void)applicationDidBecomeActive:(UIApplication *)application {
    [[NSNotificationCenter defaultCenter] postNotificationName:APP_REFRESH_NOTIFICATION object:nil];
}

在我的 View Controller 中:

- (void)viewDidLoad {
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(doStuff) postNotificationName:APP_REFRESH_NOTIFICATION object:self];
}

- (void)doStuff 永远不会被调用。为什么？

Answer 1

我假设您输入的问题不正确，您打算编写 addObserver:selector:name:object:，而不是 addObserver:selector: postNotificationName:object:(不存在这样的方法)

在的文档中- (void)addObserver:(id)notificationObserver selector:(SEL)notificationSelector name:(NSString *)notificationName object:(id)notificationSender我们可以阅读:

notificationSender

The object whose notifications the observer wants to receive; that is, only notifications sent by this sender are delivered to the observer. If you pass nil, the notification center doesn’t use a notification’s sender to decide whether to deliver it to the observer.

所以在您的情况下，当您在 postNotificationName:object: 中传递 object:nil 时，您还必须设置 object:nil 在 addObserver:selector:name:object: 中。

根据文档，您还应该将方法 doStuff 替换为:

- (void)doStuff:(NSNotification *)notification

并在 addObserver:selector:name:object: 中使用 @selector(doStuff:)。