快速出现键盘时移动文本字段

问题描述

我正在使用 Swift 进行 iOS 编程，并且我正在使用此代码来移动 UITextField，但它不起作用.我正确调用了 keyboardWillShow 函数，但文本字段没有移动.我正在使用自动布局.

I'm using Swift for programing with iOS and I'm using this code to move the UITextField, but it does not work. I call the function keyboardWillShow correctly, but the textfield doesn't move. I'm using autolayout.

override func viewDidLoad() {
    super.viewDidLoad()
    NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillShow:"), name:UIKeyboardWillShowNotification, object: nil);
    NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillHide:"), name:UIKeyboardWillHideNotification, object: nil);
}

deinit {
    NSNotificationCenter.defaultCenter().removeObserver(self);
}

func keyboardWillShow(notification: NSNotification) {
    if let keyboardSize = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue() {
        //let contentInsets = UIEdgeInsets(top: 0, left: 0, bottom: keyboardSize.height, right: 0)

        var frame = self.ChatField.frame
        frame.origin.y = frame.origin.y - keyboardSize.height + 167
        self.chatField.frame = frame
        println("asdasd")
    }
}

推荐答案

对现有答案有一些改进.

There are a couple of improvements to be made on the existing answers.

首先，UIKeyboardWillChangeFrameNotification 可能是最好的通知，因为它处理的变化不仅仅是显示/隐藏，而是由于键盘变化(语言、使用第 3 方键盘等)和旋转而引起的变化(但注意下面的注释表明键盘将隐藏也应处理以支持硬件键盘连接).

Firstly the UIKeyboardWillChangeFrameNotification is probably the best notification as it handles changes that aren't just show/hide but changes due to keyboard changes (language, using 3rd party keyboards etc.) and rotations too (but note comment below indicating the keyboard will hide should also be handled to support hardware keyboard connection).

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.

Secondly the animation parameters can be pulled from the notification to ensure that animations are properly together.

可能有一些选项可以更多地清理此代码，特别是如果您对强制解开字典代码感到满意.

There are probably options to clean up this code a bit more especially if you are comfortable with force unwrapping the dictionary code.

 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)
   }
}

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