ios - KeyboardWillShowNotification 被调用三次

Question

我需要在键盘可见后立即向上移动 UIView。但我现在面临的问题是，当我使用自定义键盘(例如 SwiftKey)时，我的 UIKeyboardWillShowNotification 被调用了三次，这导致动画效果不佳。
有没有办法只处理最后一个通知？我可以轻松躲避第一个，因为高度为 0，但第二个看起来像一个有效高度，我找不到如何解决这个问题的答案。
这是我到目前为止的内容:

override func viewDidLoad() {
    super.viewDidLoad()

    NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillAppear:", name: UIKeyboardWillShowNotification, object: nil)
    NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillDisappear:", name: UIKeyboardWillHideNotification, object: nil)
}

override func viewWillDisappear(animated: Bool) {
    super.viewWillDisappear(animated)

    NSNotificationCenter.defaultCenter().removeObserver(self)
}

func keyboardWillAppear(notification: NSNotification){
    print("keyboard appear")
    if let keyboardSize = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.CGRectValue() {
        print("with height: \(keyboardSize.height)")
        if keyboardSize.height == 0.0 {
            return
        }
        self.txtViewBottomSpace.constant = keyboardSize.height
        UIView.animateWithDuration(0.4, animations: { () -> Void in
            self.view.layoutIfNeeded()
        })
    }
}

func keyboardWillDisappear(notification: NSNotification){
    print("Keyboard disappear")
    self.txtViewBottomSpace.constant = 0.0
    UIView.animateWithDuration(0.4, animations: { () -> Void in
        self.view.layoutIfNeeded()
    })
}

我的日志输出是:

keyboard appear
with height: 0.0
keyboard appear
with height: 216.0
keyboard appear
with height: 258.0
Keyboard disappear

那么有没有办法只处理第三个通知而“忽略”前两个？

Answer 1

将以下所有字段设置为 NO 可以解决此问题。

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