CFNotificationCenterRemoveEveryObserver不删除观察者

Question

我正在使用CFNotificationCenterAddObserver（）函数注册通知，如下所示

CFNotificationCenterAddObserver(CFNotificationCenterGetDarwinNotifyCenter(),
                                NULL,
                                ringerSwitched,
                                CFSTR("com.apple.springboard.ringerstate"),
                                NULL,
                                CFNotificationSuspensionBehaviorDeliverImmediately);

稍后我会通过CFNotificationCenterRemoveEveryObserver（）函数删除它，如下所示，但仍然会调用回调方法。

CFNotificationCenterRemoveEveryObserver(CFNotificationCenterGetDarwinNotifyCenter(), NULL);

我还使用CFNotificationCenterRemoveObserver（）函数取消注册但没有用。

CFNotificationCenterRemoveObserver (CFNotificationCenterGetDarwinNotifyCenter(), NULL, CFSTR("com.apple.springboard.ringerstate"), NULL);

Answer 1

为观察者提供标识符。

CFNotificationCenterAddObserver(CFNotificationCenterGetDarwinNotifyCenter(),
                            "observer identifier",
                            ringerSwitched,
                            CFSTR("com.apple.springboard.ringerstate"),
                            NULL,
                            CFNotificationSuspensionBehaviorDeliverImmediately);

CFNotificationCenterRemoveEveryObserver(CFNotificationCenterGetDarwinNotifyCenter(), @"observer identifier");