Swift 5解决方案frédéric-adda:

protocol KeyboardHandler: class {
    var bottomConstraint: NSLayoutConstraint! { get set }
    
    func keyboardWillShow(_ notification: Notification)
    func keyboardWillHide(_ notification: Notification)
    func startObservingKeyboardChanges()
    func stopObservingKeyboardChanges()
}


extension KeyboardHandler where Self: UIViewController {

    func startObservingKeyboardChanges() {

        // NotificationCenter observers
        NotificationCenter.default.addObserver(forName: UIResponder.keyboardWillShowNotification, object: nil, queue: nil) { [weak self] notification in
          self?.keyboardWillShow(notification)
        }

        // Deal with rotations
        NotificationCenter.default.addObserver(forName: UIResponder.keyboardWillChangeFrameNotification, object: nil, queue: nil) { [weak self] notification in
          self?.keyboardWillShow(notification)
        }

        // Deal with keyboard change (emoji, numerical, etc.)
        NotificationCenter.default.addObserver(forName: UITextInputMode.currentInputModeDidChangeNotification, object: nil, queue: nil) { [weak self] notification in
          self?.keyboardWillShow(notification)
        }

        NotificationCenter.default.addObserver(forName: UIResponder.keyboardWillHideNotification, object: nil, queue: nil) { [weak self] notification in
          self?.keyboardWillHide(notification)
        }
    }


    func keyboardWillShow(_ notification: Notification) {

      let verticalPadding: CGFloat = 20 // Padding between the bottom of the view and the top of the keyboard

        guard let value = notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue else { return }
      let keyboardHeight = value.cgRectValue.height

      // Here you could have more complex rules, like checking if the textField currently selected is actually covered by the keyboard, but that's out of this scope.
      self.bottomConstraint.constant = keyboardHeight + verticalPadding

      UIView.animate(withDuration: 0.1, animations: { () -> Void in
          self.view.layoutIfNeeded()
      })
  }


  func keyboardWillHide(_ notification: Notification) {
      self.bottomConstraint.constant = 0

      UIView.animate(withDuration: 0.1, animations: { () -> Void in
          self.view.layoutIfNeeded()
      })
  }


  func stopObservingKeyboardChanges() {
      NotificationCenter.default.removeObserver(self)
  }
}

在任何UIViewController中:

遵循KeyboardHandler协议

extension AnyViewController: KeyboardHandler {} 

为屏幕上最后一个底部元素添加底部约束。

@IBOutlet var bottomConstraint: NSLayoutConstraint! 

添加观察者订阅/取消订阅:

 override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        startObservingKeyboardChanges()
 }
    
 override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        stopObservingKeyboardChanges()
 }

享受吧!

如果视图上有多个文本字段，那么我建议您查看这个方法。当在字段之间切换时，你不会有视图跑开的问题，它会简单地适应所需的文本字段。它在swift 5中工作

  override func viewDidLoad() {
    super.viewDidLoad()
    registerForKeyboardNotification()
}

扩展中的所有方法

extension StartViewController: UITextFieldDelegate {

func registerForKeyboardNotification() {
    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(sender:)), name: UIResponder.keyboardWillShowNotification, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(sender:)), name: UIResponder.keyboardWillHideNotification, object: nil) 
}

@objc func keyboardWillShow(sender: NSNotification) {
    guard let userInfo = sender.userInfo,
          let keyboardFrame = userInfo[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue,
          let currentTextField = UIResponder.currentFirst() as? UITextField  else { return }
         
    let keyboardTopY = keyboardFrame.cgRectValue.origin.y
    let convertedTextFieldFrame = view.convert(currentTextField.frame, from: currentTextField.superview)
    let textFieldBottomY = convertedTextFieldFrame.origin.y + convertedTextFieldFrame.size.height
    
    if textFieldBottomY > keyboardTopY {
        let textBoxY = convertedTextFieldFrame.origin.y
        let newFrameY = (textBoxY - keyboardTopY / 2) * -1
        view.frame.origin.y = newFrameY
    }
}


@objc func keyboardWillHide(sender: NSNotification) {
     self.view.frame.origin.y = 0
}


func textFieldShouldReturn(_ textField: UITextField) -> Bool {
    switch textField {
    case emailTextField :
        passwordTextField.becomeFirstResponder()
    default:
        emailTextField.becomeFirstResponder()  
    }
    return true
}

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    super.touchesBegan(touches , with:event)
    view.endEditing(true)
}
}

最后我们用UIResponder建立方法

extension UIResponder {
private struct Static {
    static weak var responder: UIResponder?
}

static func currentFirst() -> UIResponder? {
    Static.responder = nil
    UIApplication.shared.sendAction(#selector(UIResponder._trap), to: nil, from: nil, for: nil)
    return Static.responder
}

@objc private func _trap() {
    Static.responder = self
}
}

一个简单的解决方案是移动视图与键盘高度常数。

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);
}

@objc func keyboardWillShow(sender: NSNotification) {
     self.view.frame.origin.y = -150 // Move view 150 points upward 
}

@objc func keyboardWillHide(sender: NSNotification) {
     self.view.frame.origin.y = 0 // Move view to original position  
}

斯威夫特5:

NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(sender:)), name: UIResponder.keyboardWillShowNotification, object: nil);

NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(sender:)), name: UIResponder.keyboardWillHideNotification, object: nil);

这是一个通用的解决方案，为所有的TextField 步骤,

1)创建一个由其他ViewController扩展的通用ViewController

override func viewDidLoad() {
    super.viewDidLoad()
    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide), name: UIResponder.keyboardWillHideNotification, object: nil)

}
 @objc func keyboardWillShow(notification: NSNotification) {
    if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
        if self.view.frame.origin.y == 0 {
            self.view.frame.origin.y -= getMoveableDistance(keyboarHeight: keyboardSize.height)
        }
    }
}

@objc func keyboardWillHide(notification: NSNotification) {
    if self.view.frame.origin.y != 0 {
        self.view.frame.origin.y = 0
    }
}
deinit {
    NotificationCenter.default.removeObserver(self)
}

//get the distance to move up the main view for the focus textfiled
func getMoveableDistance(keyboarHeight : CGFloat) ->  CGFloat{
    var y:CGFloat = 0.0
    if let activeTF = getSelectedTextField(){
        var tfMaxY = activeTF.frame.maxY
        var containerView = activeTF.superview!
        while containerView.frame.maxY != self.view.frame.maxY{
            let contViewFrm = containerView.convert(activeTF.frame, to: containerView.superview)
            tfMaxY = tfMaxY + contViewFrm.minY
            containerView = containerView.superview!
        }
        let keyboardMinY = self.view.frame.height - keyboarHeight
        if tfMaxY > keyboardMinY{
            y = (tfMaxY - keyboardMinY) + 10.0
        }
    }

    return y
}

2)创建UIViewController和当前激活的TextField的扩展

//get active text field

扩展 UIViewController { func getSelectedTextField（） -> UITextField？{

    let totalTextFields = getTextFieldsInView(view: self.view)

    for textField in totalTextFields{
        if textField.isFirstResponder{
            return textField
        }
    }

    return nil

}

func getTextFieldsInView(view: UIView) -> [UITextField] {

    var totalTextFields = [UITextField]()

    for subview in view.subviews as [UIView] {
        if let textField = subview as? UITextField {
            totalTextFields += [textField]
        } else {
            totalTextFields += getTextFieldsInView(view: subview)
        }
    }

    return totalTextFields
}

}

非常简单，不需要编写更多代码。 只需在podfile中添加pod 'IQKeyboardManagerSwift'，并在AppDelegate页面中添加下面的代码。

import IQKeyboardManagerSwift

在方法didFinishLaunchingWithOptions()类型中

IQKeyboardManager.shared.enable = true

就是这样。 查看这个视频链接，以更好地了解https://youtu.be/eOM94K1ZWN8 希望这对你有所帮助。

我已采取以下方式:

当textfield superview为view时，这很有用

class AdminLoginViewController: UIViewController,
UITextFieldDelegate{

    @IBOutlet weak var txtUserName: UITextField!
    @IBOutlet weak var txtUserPassword: UITextField!
    @IBOutlet weak var btnAdminLogin: UIButton!

    private var activeField : UIView?

    var param:String!
    var adminUser : Admin? = nil
    var kbHeight: CGFloat!

    override func viewDidLoad()
    {
        self.addKeyBoardObserver()
        self.addGestureForHideKeyBoard()
    }

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

    func addGestureForHideKeyBoard()
    {
        let tapGesture = UITapGestureRecognizer(target: self, action: Selector("hideKeyboard"))
        tapGesture.cancelsTouchesInView = false
        view.addGestureRecognizer(tapGesture)
    }

    func hideKeyboard() {
        self.view.endEditing(true)
    }

    func addKeyBoardObserver(){

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

    func removeObserver(){
        NSNotificationCenter.defaultCenter().removeObserver(self)
    }

    //MARK:- textfiled Delegate

    func textFieldShouldBeginEditing(textField: UITextField) -> Bool
    {
         activeField = textField

        return true
    }
    func textFieldShouldEndEditing(textField: UITextField) -> Bool
    {
        if activeField == textField
        {
            activeField = nil
        }

        return true
    }

    func textFieldShouldReturn(textField: UITextField) -> Bool {

        if txtUserName == textField
        {
            txtUserPassword.becomeFirstResponder()
        }
        else if (textField == txtUserPassword)
        {
            self.btnAdminLoginAction(nil)
        }
        return true;
    }

    func willChangeKeyboardFrame(aNotification : NSNotification)
    {
       if self.activeField != nil && self.activeField!.isFirstResponder()
    {
        if let keyboardSize =  (aNotification.userInfo![UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue()
        {
            let dy = (self.activeField?.superview?.convertRect((self.activeField?.frame)!, toView: view).origin.y)!

            let height = (self.view.frame.size.height - keyboardSize.size.height)

            if dy > height
            {
                var frame = self.view.frame

                frame.origin.y = -((dy - height) + (self.activeField?.frame.size.height)! + 20)

                self.view.frame = frame
            }
        }
    }
    else
    {
        var frame = self.view.frame
        frame.origin.y = 0
        self.view.frame = frame
    }
    } }