Ios UIKeyboard将显示来自其他应用程序的通知

我的应用程序使用

UIKeyboardWillShow

和

UIKeyboardWillHide

通知来监控键盘的更改，从而为用户界面的特定部分设置动画

我遇到的问题是，当我从显示键盘的Messages应用程序切换到使用应用程序切换器的应用程序时（在不需要键盘的状态下），它将触发

UI键盘将显示

通知，然后

UI键盘将隐藏

通知，这将导致我的UI上下跳动一点

有没有办法只监听你自己应用程序的键盘通知

视图将出现

    NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillShow:", name: UIKeyboardWillShowNotification, object: nil)
    NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillChange:", name: UIKeyboardWillChangeFrameNotification, object: nil)
    NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillHide:", name: UIKeyboardWillHideNotification, object: nil)

    NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillShowNotification, object: nil)
    NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillHideNotification, object: nil)
    NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillChangeFrameNotification, object: nil)

视图将消失

    NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillShow:", name: UIKeyboardWillShowNotification, object: nil)
    NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillChange:", name: UIKeyboardWillChangeFrameNotification, object: nil)
    NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillHide:", name: UIKeyboardWillHideNotification, object: nil)

    NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillShowNotification, object: nil)
    NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillHideNotification, object: nil)
    NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillChangeFrameNotification, object: nil)

有密码吗？ 您是在整个应用程序中观察键盘，还是仅在

viewcontroller

中观察键盘

当您不想收听更改时，您可以

removeObserver

- (void)applicationDidEnterBackground:(UIApplication *)application
{
    [[NSNotificationCenter defaultCenter] removeObserver:yourClass name:UIKeyboardWillShowNotification object:nil];
    [[NSNotificationCenter defaultCenter] removeObserver:yourClass name:UIKeyboardWillHideNotification object:nil];
}

---

但是要小心，您需要正确使用通知中心。

我今天遇到了这个问题。我最后做的是添加观察者来检测应用程序何时进入和离开后台。如果进入后台，则移除键盘观察者，否则添加键盘观察者。像这样的。。。我相信有更好的方法，但这对我来说很有效。希望这有帮助

override func viewDidLoad() {
    super.viewDidLoad()
    registerForPreviewing(with: self, sourceView: collectionView)
    addApplicationStateObservers()
}

override func viewDidAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    addKeyboardObservers()
}

override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)
    removeKeyboardObservers()
}

deinit {
    removeApplicationStateObservers()
    removeKeyboardObservers()
}

func applicationIsActive() {
    let delay = DispatchTime.now() + 0.1
    DispatchQueue.main.asyncAfter(deadline: delay) {
        self.addKeyboardObservers()
    }
}

// Observers 
// Application state observers were add to handle edge case scenario where if user is playing a video in expanded pip view on iPhone, if user switchs to another app with keyboard then switch back, the video will disppears. Our app removes and re-adds observer as user enter and exit the app. 

func addApplicationStateObservers() {
    NotificationCenter.default.addObserver(self, selector: #selector(applicationIsActive), name: .UIApplicationDidBecomeActive, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(removeKeyboardObservers), name: .UIApplicationDidEnterBackground, object: nil)
}

func removeApplicationStateObservers() {
    NotificationCenter.default.removeObserver(self, name: .UIApplicationDidBecomeActive, object: nil)
    NotificationCenter.default.removeObserver(self, name: .UIApplicationDidEnterBackground, object: nil)
}

func addKeyboardObservers() {
    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWasShown), name: .UIKeyboardWillShow, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillBeHidden), name: .UIKeyboardWillHide, object: nil)
}

func removeKeyboardObservers() {
    NotificationCenter.default.removeObserver(self, name: .UIKeyboardWillShow, object: nil)
    NotificationCenter.default.removeObserver(self, name: .UIKeyboardWillHide, object: nil)
}

---

谢谢你的回复。我只在ViewController中监视它。我将观察员添加到ViewWillExample（上面添加的代码）中，现在已将remove observer添加到ViewWillEnglish中，但当您切换回时，仍然无法获取键盘显示触发器。您确定离开应用程序时将执行“ViewWillEnglishe”中的代码吗？尝试在

视图中提供
NSLog
以进行监视。这与您的要求无关，但您可能需要记住
视图将出现
并不一定意味着您的视图确实会出现（我认为这是一个恼人的错误，甚至是一个巨大的错误，但这是生活中的事实），而
视图将消失
并不一定意味着您的视图将确实消失。因此，您最好将这些方法移动到
viewDid
，这意味着它所说的内容