当我的应用程序中出现键盘时，按钮部分向上移动（仅按钮的文本移动）

Question

我的swift 应用程序中有一个按钮，它位于屏幕底部。它的约束是：

我还为将按钮与屏幕底部分开的约束附加了插座：

当我运行应用程序时，我看到了我的按钮（我添加了一些背景颜色，以便我的示例清晰可见）：

现在，奇怪的事情发生了——当键盘显示时，按钮上的文字向上移动，蓝色背景保持在原来的位置：

而且按钮的可见部分根本不可点击。

这是我的实现中的某种错误还是问题？

我的代码很简单：

@IBOutlet weak var continueUsernameBottomConstraint: NSLayoutConstraint!

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


    NotificationCenter.default.addObserver(self, selector: #selector(tutorialKeyboardWillAppear), name: .UIKeyboardWillShow, object: nil)

    NotificationCenter.default.addObserver(self, selector: #selector(tutorialKeyboardWillDisappear), name: .UIKeyboardWillHide, object: nil)

}


func tutorialKeyboardWillAppear(notification: NSNotification){
    print("KEYBOARD APPEARS")
    let endFrame = ((notification as NSNotification).userInfo![UIKeyboardFrameEndUserInfoKey] as! NSValue).cgRectValue

    continueUsernameBottomConstraint.constant = view.bounds.height - endFrame.origin.y

    self.view.layoutIfNeeded()
}

func tutorialKeyboardWillDisappear(notification: NSNotification){

    print("KEYBOARD DISAPPEARS")
    let endFrame = ((notification as NSNotification).userInfo![UIKeyboardFrameEndUserInfoKey] as! NSValue).cgRectValue

    continueUsernameBottomConstraint.constant = view.bounds.height - endFrame.origin.y

    self.view.layoutIfNeeded()

}

Answer 1

使用这个

func tutorialKeyboardWillAppear(notification: NSNotification){
    print("KEYBOARD APPEARS")
    let endFrame = ((notification as NSNotification).userInfo![UIKeyboardFrameEndUserInfoKey] as! NSValue).cgRectValue
    continueUsernameBottomConstraint.constant = continueUsernameBottomConstraint.constant + CGFloat(endFrame.height)
    self.view.layoutIfNeeded()
}

func tutorialKeyboardWillDisappear(notification: NSNotification){

    print("KEYBOARD DISAPPEARS")
    let endFrame = ((notification as NSNotification).userInfo![UIKeyboardFrameEndUserInfoKey] as! NSValue).cgRectValue
    continueUsernameBottomConstraint.constant = continueUsernameBottomConstraint.constant -  CGFloat(endFrame.height)
    self.view.layoutIfNeeded()

}