可以使用这样简单的UIViewController扩展

//MARK: - Observers
extension UIViewController {

    func addObserverForNotification(notificationName: String, actionBlock: (NSNotification) -> Void) {
        NSNotificationCenter.defaultCenter().addObserverForName(notificationName, object: nil, queue: NSOperationQueue.mainQueue(), usingBlock: actionBlock)
    }

    func removeObserver(observer: AnyObject, notificationName: String) {
        NSNotificationCenter.defaultCenter().removeObserver(observer, name: notificationName, object: nil)
    }
}

//MARK: - Keyboard observers
extension UIViewController {

    typealias KeyboardHeightClosure = (CGFloat) -> ()

    func addKeyboardChangeFrameObserver(willShow willShowClosure: KeyboardHeightClosure?,
        willHide willHideClosure: KeyboardHeightClosure?) {
            NSNotificationCenter.defaultCenter().addObserverForName(UIKeyboardWillChangeFrameNotification,
                object: nil, queue: NSOperationQueue.mainQueue(), usingBlock: { [weak self](notification) in
                    if let userInfo = notification.userInfo,
                        let frame = (userInfo[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.CGRectValue(),
                        let duration = userInfo[UIKeyboardAnimationDurationUserInfoKey] as? Double,
                        let c = userInfo[UIKeyboardAnimationCurveUserInfoKey] as? UInt,
                        let kFrame = self?.view.convertRect(frame, fromView: nil),
                        let kBounds = self?.view.bounds {

                            let animationType = UIViewAnimationOptions(rawValue: c)
                            let kHeight = kFrame.size.height
                            UIView.animateWithDuration(duration, delay: 0, options: animationType, animations: {
                                if CGRectIntersectsRect(kBounds, kFrame) { // keyboard will be shown
                                    willShowClosure?(kHeight)
                                } else { // keyboard will be hidden
                                    willHideClosure?(kHeight)
                                }
                                }, completion: nil)
                    } else {
                            print("Invalid conditions for UIKeyboardWillChangeFrameNotification")
                    }
            })
    }

    func removeKeyboardObserver() {
        removeObserver(self, notificationName: UIKeyboardWillChangeFrameNotification)
    }
}

用法示例

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

        removeKeyboardObserver()
    }

override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(animated)

    addKeyboardChangeFrameObserver(willShow: { [weak self](height) in
        //Update constraints here
        self?.view.setNeedsUpdateConstraints()
        }, willHide: { [weak self](height) in
        //Reset constraints here
        self?.view.setNeedsUpdateConstraints()
    })
}

Swift 4解决方案

//MARK: - Observers
extension UIViewController {

  func addObserverForNotification(_ notificationName: Notification.Name, actionBlock: @escaping (Notification) -> Void) {
    NotificationCenter.default.addObserver(forName: notificationName, object: nil, queue: OperationQueue.main, using: actionBlock)
  }

  func removeObserver(_ observer: AnyObject, notificationName: Notification.Name) {
    NotificationCenter.default.removeObserver(observer, name: notificationName, object: nil)
  }
}

//MARK: - Keyboard handling
extension UIViewController {

  typealias KeyboardHeightClosure = (CGFloat) -> ()

  func addKeyboardChangeFrameObserver(willShow willShowClosure: KeyboardHeightClosure?,
                                      willHide willHideClosure: KeyboardHeightClosure?) {
    NotificationCenter.default.addObserver(forName: NSNotification.Name.UIKeyboardWillChangeFrame,
                                           object: nil, queue: OperationQueue.main, using: { [weak self](notification) in
                                            if let userInfo = notification.userInfo,
                                              let frame = (userInfo[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue,
                                              let duration = userInfo[UIKeyboardAnimationDurationUserInfoKey] as? Double,
                                              let c = userInfo[UIKeyboardAnimationCurveUserInfoKey] as? UInt,
                                              let kFrame = self?.view.convert(frame, from: nil),
                                              let kBounds = self?.view.bounds {

                                              let animationType = UIViewAnimationOptions(rawValue: c)
                                              let kHeight = kFrame.size.height
                                              UIView.animate(withDuration: duration, delay: 0, options: animationType, animations: {
                                                if kBounds.intersects(kFrame) { // keyboard will be shown
                                                  willShowClosure?(kHeight)
                                                } else { // keyboard will be hidden
                                                  willHideClosure?(kHeight)
                                                }
                                              }, completion: nil)
                                            } else {
                                              print("Invalid conditions for UIKeyboardWillChangeFrameNotification")
                                            }
    })
  }

  func removeKeyboardObserver() {
    removeObserver(self, notificationName: NSNotification.Name.UIKeyboardWillChangeFrame)
  }
}

斯威夫特4.2

//MARK: - Keyboard handling
extension UIViewController {

    func addObserverForNotification(_ notificationName: Notification.Name, actionBlock: @escaping (Notification) -> Void) {
        NotificationCenter.default.addObserver(forName: notificationName, object: nil, queue: OperationQueue.main, using: actionBlock)
    }

    func removeObserver(_ observer: AnyObject, notificationName: Notification.Name) {
        NotificationCenter.default.removeObserver(observer, name: notificationName, object: nil)
    }

    typealias KeyboardHeightClosure = (CGFloat) -> ()

    func removeKeyboardObserver() {
        removeObserver(self, notificationName: UIResponder.keyboardWillChangeFrameNotification)
    }

    func addKeyboardChangeFrameObserver(willShow willShowClosure: KeyboardHeightClosure?,
                                        willHide willHideClosure: KeyboardHeightClosure?) {
        NotificationCenter.default.addObserver(forName: UIResponder.keyboardWillChangeFrameNotification,
                                               object: nil, queue: OperationQueue.main, using: { [weak self](notification) in
                                                if let userInfo = notification.userInfo,
                                                    let frame = (userInfo[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue,
                                                    let duration = userInfo[UIResponder.keyboardAnimationDurationUserInfoKey] as? Double,
                                                    let c = userInfo[UIResponder.keyboardAnimationCurveUserInfoKey] as? UInt,
                                                    let kFrame = self?.view.convert(frame, from: nil),
                                                    let kBounds = self?.view.bounds {

                                                    let animationType = UIView.AnimationOptions(rawValue: c)
                                                    let kHeight = kFrame.size.height
                                                    UIView.animate(withDuration: duration, delay: 0, options: animationType, animations: {
                                                        if kBounds.intersects(kFrame) { // keyboard will be shown
                                                            willShowClosure?(kHeight)
                                                        } else { // keyboard will be hidden
                                                            willHideClosure?(kHeight)
                                                        }
                                                    }, completion: nil)
                                                } else {
                                                    print("Invalid conditions for UIKeyboardWillChangeFrameNotification")
                                                }
        })
    }
}

Well, I think i might be too late but i found another simple version of Saqib's answer. I'm using Autolayout with constraints. I have a small view inside of another main view with username and password fields. Instead of changing the y coordinate of the view i'm saving the original constraint value in a variable and changing the constraint's constant to some value and again after the keyboard dismisses, i'm setting up the constraint to original one. This way it avoids the problem Saqib's answer has, (The view keeps on moving up and does not stop). Below is my code...

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);
    self.originalConstraint = self.centerYConstraint.constant
  }

  func keyboardWillShow(sender: NSNotification) {
    self.centerYConstraint.constant += 30
  }

  func keyboardWillHide(sender: NSNotification) {
    self.centerYConstraint.constant = self.originalConstraint
  }

下面是一个简单的解决方案，其中文本字段有一个约束将其绑定到底部布局指南。它只是将键盘高度添加到约束常数中。

// This constraint ties the text field to the bottom layout guide
@IBOutlet var textFieldToBottomLayoutGuideConstraint: NSLayoutConstraint!

override func viewDidLoad() {
    super.viewDidLoad()

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

func keyboardWillShow(sender: NSNotification) {
    if let keyboardSize = (sender.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue() {
        self.textFieldToBottomLayoutGuideConstraint?.constant += keyboardSize.height
    }
}

func keyboardWillHide(sender: NSNotification) {
    if let keyboardSize = (sender.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue() {
        self.textFieldToBottomLayoutGuideConstraint?.constant -= keyboardSize.height
    }
}

以下是我对Swift 2.2的解决方案:

首先注册键盘显示/隐藏通知

NSNotificationCenter.defaultCenter().addObserver(self,
                                                 selector: #selector(MessageThreadVC.keyboardWillShow(_:)),
                                                 name: UIKeyboardWillShowNotification,
                                                 object: nil)
NSNotificationCenter.defaultCenter().addObserver(self,
                                                 selector: #selector(MessageThreadVC.keyboardWillHide(_:)),
                                                 name: UIKeyboardWillHideNotification,
                                                 object: nil)

然后在与这些通知相对应的方法中，向上或向下移动主视图

func keyboardWillShow(sender: NSNotification) {
if let keyboardSize = (sender.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.CGRectValue() {
  self.view.frame.origin.y = -keyboardSize.height
  }
}

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

诀窍在于“keyboardWillShow”部分，每次“QuickType建议栏”被展开或折叠时，该部分都会被调用。然后我们总是设置主视图的y坐标等于键盘总高度的负值(包括或不包括“QuickType栏”部分)。

最后不要忘记删除观察者

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

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
}
}

这是一个改进版的@JosephLord和@Hlung的回答。 无论你是否有标签栏，它都适用。 并且它可以完美地恢复由键盘移动到原始位置的视图。

// You have to set this up in storyboard first!. 
// It's a vertical spacing constraint between view and bottom of superview.
@IBOutlet weak var bottomSpacingConstraint: NSLayoutConstraint! 

override func viewDidLoad() {
        super.viewDidLoad()            

        //    Receive(Get) Notification
        NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardNotification:", name: UIKeyboardWillShowNotification, object: nil)
        NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardNotification:", name: UIKeyboardWillHideNotification, object: nil)


        self.originalConstraint = self.keyboardHeightLayoutConstraint?.constant //for original coordinate.
}

func keyboardNotification(notification: NSNotification) {
        let isShowing = notification.name == UIKeyboardWillShowNotification

        var tabbarHeight: CGFloat = 0
        if self.tabBarController? != nil {
            tabbarHeight = self.tabBarController!.tabBar.frame.height
        }
        if let userInfo = notification.userInfo {
            let endFrame = (userInfo[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.CGRectValue()
            let duration:NSTimeInterval = (userInfo[UIKeyboardAnimationDurationUserInfoKey] as? NSNumber)?.doubleValue ?? 0
            let animationCurveRawNSN = userInfo[UIKeyboardAnimationCurveUserInfoKey] as? NSNumber
            let animationCurveRaw = animationCurveRawNSN?.unsignedLongValue ?? UIViewAnimationOptions.CurveEaseInOut.rawValue
            let animationCurve:UIViewAnimationOptions = UIViewAnimationOptions(rawValue: animationCurveRaw)
            self.keyboardHeightLayoutConstraint?.constant = isShowing ? (endFrame!.size.height - tabbarHeight) : self.originalConstraint!
            UIView.animateWithDuration(duration,
                delay: NSTimeInterval(0),
                options: animationCurve,
                animations: { self.view.layoutIfNeeded() },
                completion: nil)
        }
}