即使观察者被移除，通知观察者也会被多次调用 [英] Notification observer called multiple times even though the observer is removed

问题描述

当应用程序处于后台模式或手机处于睡眠状态并且接收到 VoIP 推送时，AppDelagte 中的以下函数会引导用户(到应用程序中的 UserTableViewController)并发布通知.

When the app is in background mode or phone is in sleep state and a VoIp push is received the below function in AppDelagte directs the user (to the UserTableViewController in the app) and posts a notification.

UserTableViewController 的 viewDidLoad 中的通知观察者观察通知并调用 funcsimulateMyIncomingCallFromNotification.

A notification observer in viewDidLoad of the UserTableViewController observes the notification and calls the func simulateMyIncomingCallFromNotification.

我注意到当我第二次发送 VoIP 推送时，func simulationMyIncomingCallFromNotification 被调用两次，第三次，三次，依此类推.如何避免多次调用?

I noticed that when I send a VoIP push the second time the func simulateMyIncomingCallFromNotification is called twice and on the third time, thrice and so on. How can I avoid multiple calls ?

其他 SO 答案，建议删除通知观察者，我什至在设置之前就已经这样做了，正如您在下面的扩展中看到的那样，但这似乎并没有解决我的问题.

Other SO answers, advised to remove the Notification observer, which I am doing even before setting one, as you can seen in the below extension, but this doesn't seem to solve my problem.

我该如何解决这个问题?

How could I resolve this issue ?

在 AppDelegate 中:

func pushRegistry(_ registry: PKPushRegistry, didReceiveIncomingPushWith payload: PKPushPayload, forType type: PKPushType) {

 let storyboard = UIStoryboard(name: "User", bundle: nil)

 VC = storyboard.instantiateViewController(withIdentifier: "UserTableViewController") as! UserTableViewController

 self.window = UIWindow(frame: UIScreen.main.bounds)
        self.window?.rootViewController = VC
        self.window?.makeKeyAndVisible()


NotificationCenter.default.post(name: Notification.Name("didReceiveIncomingVoipPush"), object: nil, userInfo: payloadDict)
}

在 UserTableViewController

extension NotificationCenter {
    func setObserver(_ observer: AnyObject, selector: Selector, name: NSNotification.Name, object: AnyObject?) {
        print("NotificationCenter.default before: \(NotificationCenter.default)")
        NotificationCenter.default.removeObserver(observer, name: name, object: object)
        NotificationCenter.default.addObserver(observer, selector: selector, name: name, object: object)
        print("NotificationCenter.default after: \(NotificationCenter.default)")
    }
}

fun viewDidLoad(){

NotificationCenter.default.setObserver(self, selector: #selector(self.simulateMyIncomingCallFromNotification(notification:)), name: Notification.Name("didReceiveIncomingVoipPush"), object: nil)

}

推荐答案

Apple 建议观察者应该在 viewWillAppear 中注册，在 viewWillDissapear 中取消注册.

Apple recommends that observers should be registered in viewWillAppear and unregistered in viewWillDissapear.

你能不能试试这个.

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