Ios 快速出现键盘 timeshift 动文本字段

在现有答案的基础上有几点需要改进.

首先，UIKeyboardWillChangeFrameNotification可能是最好的通知，因为它处理的更改不只是显示/隐藏，而是由于键盘更改(语言、使用第三方键盘等)而更改.也可以旋转(但请注意下面指示键盘将隐藏的注释也应进行处理，以支持硬件键盘连接).

其次，可以从通知中提取动画参数，以确保动画正确组合在一起.

可能有一些选项可以更彻底地清理这段代码，尤其是如果您对强制展开字典代码感到满意的话.

 class MyViewController: UIViewController {

   // This constraint ties an element at zero points from the bottom layout guide
   @IBOutlet var keyboardHeightLayoutConstraint: NSLayoutConstraint?
 
   override func viewDidLoad() {
     super.viewDidLoad()
     NotificationCenter.default.addObserver(self,
       selector: #selector(self.keyboardNotification(notification:)),
       name: UIResponder.keyboardWillChangeFrameNotification,
       object: nil)
   }
 
   deinit {
     NotificationCenter.default.removeObserver(self)
   }
 
   @objc func keyboardNotification(notification: NSNotification) {
     guard let userInfo = notification.userInfo else { return }

     let endFrame = (userInfo[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue
     let endFrameY = endFrame?.origin.y ?? 0
     let duration:TimeInterval = (userInfo[UIResponder.keyboardAnimationDurationUserInfoKey] as? NSNumber)?.doubleValue ?? 0
     let animationCurveRawNSN = userInfo[UIResponder.keyboardAnimationCurveUserInfoKey] as? NSNumber
     let animationCurveRaw = animationCurveRawNSN?.uintValue ?? UIView.AnimationOptions.curveEaseInOut.rawValue
     let animationCurve:UIView.AnimationOptions = UIView.AnimationOptions(rawValue: animationCurveRaw)

     if endFrameY >= UIScreen.main.bounds.size.height {
       self.keyboardHeightLayoutConstraint?.constant = 0.0
     } else {
       self.keyboardHeightLayoutConstraint?.constant = endFrame?.size.height ?? 0.0
     }

     UIView.animate(
       withDuration: duration,
       delay: TimeInterval(0),
       options: animationCurve,
       animations: { self.view.layoutIfNeeded() },
       completion: nil)
   }
}