UIKeyboardWillShowNotification被调用三次

Question

一旦键盘变得可见，我需要移动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被调用三次，导致动画效果不佳。 有办法只处理最后一次通知吗？我可以很容易地躲避第一个，因为高度为0，但第二个看起来像一个有效的高度，我找不到如何解决这个问题的答案。 这是我到目前为止：

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：

键盘出现 高度：0.0 键盘出现 身高：216.0 键盘出现 身高：258.0 键盘消失了

那么有没有办法只处理第三个通知并“忽略”前两个？

Answer 1

更改通知名称UIKeyboardDidShowNotification和UIKeyboardDidHideNotification然后解决问题

 override func viewDidLoad() {
    super.viewDidLoad()

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

Answer 2

我建议用userInfo下通知的UIKeyboardAnimationDurationUserInfoKey字典中的键盘动画持续时间替换静态动画持续时间（0.4）。这样，您的动画将与键盘动画同步。您还可以使用UIKeyboardAnimationCurveUserInfoKey键检索键盘使用的动画曲线。

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

func keyboardWillDisappear(notification: NSNotification){
    print("Keyboard disappear")
    let animationDuration = notification.userInfo?[UIKeyboardAnimationDurationUserInfoKey]?.doubleValue;
    self.txtViewBottomSpace.constant = 0.0
        UIView.animateWithDuration(animationDuration!, delay: 0.0, options: .BeginFromCurrentState, animations: { () -> Void in
        self.view.layoutIfNeeded()
    })
}

Answer 3

这是因为键盘可以有不同的尺寸，特别是第三方。因此，您收到的第一个通知将始终为默认系统高度，之后您收到的任何通知将包括第三方键盘扩展的新高度（如果已加载）。为了解决这个问题，在处理通知的方法中，您需要先获取高度，然后将其设置为默认高度（我认为226）。然后将变量设置为此第一个高度，然后对结果调用通知方法，您可以检查新高度是否大于原始高度，如果是，您可以找到增量，然后相应地重新调整帧。

Answer 4

将所有波纹管字段设置为NO可以解决此问题。

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