编辑:我推荐一个更简单、更干净的解决方案。只需将底部间距约束的类更改为KeyboardLayoutConstraint。它会自动展开到键盘高度。

这是一个改进版的@JosephLord的回答。

在iOS 8.3 iPad模拟器上测试，Portrait。Xcode6.3 beta4，我发现他的答案不工作时，键盘隐藏，因为UIKeyboardFrameEndUserInfoKey是“NSRect:{{0, 1024}，{768, 264}}”;高度不为0。

这回到使用传统的UIKeyboardWillShowNotification和UIKeyboardWillHideNotification来更好地判断键盘何时隐藏，而不是依赖于结束帧的高度。UIKeyboardWillShowNotification也会在键盘帧改变时发送，所以它应该覆盖所有的用例。

    // 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()

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

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

    func keyboardNotification(notification: NSNotification) {

        let isShowing = notification.name == UIKeyboardWillShowNotification

        if let userInfo = notification.userInfo {
            let endFrame = (userInfo[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.CGRectValue()
            let endFrameHeight = endFrame?.size.height ?? 0.0
            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.bottomSpacingConstraint?.constant = isShowing ? endFrameHeight : 0.0
            UIView.animateWithDuration(duration,
                delay: NSTimeInterval(0),
                options: animationCurve,
                animations: { self.view.layoutIfNeeded() },
                completion: nil)
        }
    }

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);

我喜欢简洁的Swift代码。这是我能想出的最严格的代码，可以用键盘上下移动文本视图。它目前正在iOS8/9 Swift 2生产应用程序中运行。

更新(2016年3月): 我只是尽可能地压缩了之前的代码。此外，这里还有一些流行的答案，它们硬编码了键盘高度和动画参数。这是没有必要的，更不用说这些答案中的数字并不总是与我在6s+ iOS9上看到的实际值一致(键盘高度226，持续时间0.25，动画曲线7)。在任何情况下，几乎不需要额外的代码来直接从系统获取这些值。见下文。

override func viewDidLoad() {
    super.viewDidLoad()

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

func animateWithKeyboard(notification: NSNotification) {

    // Based on both Apple's docs and personal experience, 
    // I assume userInfo and its documented keys are available.
    // If you'd like, you can remove the forced unwrapping and add your own default values.

    let userInfo = notification.userInfo!
    let keyboardHeight = (userInfo[UIKeyboardFrameEndUserInfoKey] as! NSValue).CGRectValue().height
    let duration = userInfo[UIKeyboardAnimationDurationUserInfoKey] as! Double
    let curve = userInfo[UIKeyboardAnimationCurveUserInfoKey] as! UInt
    let moveUp = (notification.name == UIKeyboardWillShowNotification)

    // baseContraint is your Auto Layout constraint that pins the
    // text view to the bottom of the superview.

    baseConstraint.constant = moveUp ? -keyboardHeight : 0

    let options = UIViewAnimationOptions(rawValue: curve << 16)
    UIView.animateWithDuration(duration, delay: 0, options: options,
        animations: {
            self.view.layoutIfNeeded()
        },
        completion: nil
    )

}

注意:这段代码涵盖了大多数注释/一般情况。然而，处理不同的方向和/或自定义键盘可能需要更多的代码。如果你需要处理每一个场景，这可能会有所帮助。

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
}
}

我修改了一点@Simpa解决方案.........

override func viewDidLoad() 
{

    super.viewDidLoad()
    NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("makeSpaceForKeyboard:"), name:UIKeyboardWillShowNotification, object: nil);
    NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("makeSpaceForKeyboard:"), name:UIKeyboardWillHideNotification, object: nil);
}

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

var keyboardIsVisible = false
override func makeSpaceForKeyboard(notification: NSNotification) {

    let info = notification.userInfo!
    let keyboardHeight:CGFloat = (info[UIKeyboardFrameEndUserInfoKey] as! NSValue).CGRectValue().size.height
    let duration:Double = info[UIKeyboardAnimationDurationUserInfoKey] as! Double

    if notification.name == UIKeyboardWillShowNotification && keyboardIsVisible == false{

        keyboardIsVisible = true

        UIView.animateWithDuration(duration, animations: { () -> Void in
            var frame = self.view.frame
            frame.size.height = frame.size.height - keyboardHeight
            self.view.frame = frame
        })

    } else if keyboardIsVisible == true && notification.name == UIKeyboardWillShowNotification{

    }else {
        keyboardIsVisible = false

        UIView.animateWithDuration(duration, animations: { () -> Void in
            var frame = self.view.frame
            frame.size.height = frame.size.height + keyboardHeight
            self.view.frame = frame
        })
    }
}

struct MoveKeyboard {
    static let KEYBOARD_ANIMATION_DURATION : CGFloat = 0.3
    static let MINIMUM_SCROLL_FRACTION : CGFloat = 0.2;
    static let MAXIMUM_SCROLL_FRACTION : CGFloat = 0.8;
    static let PORTRAIT_KEYBOARD_HEIGHT : CGFloat = 216;
    static let LANDSCAPE_KEYBOARD_HEIGHT : CGFloat = 162;
}


  func textFieldDidBeginEditing(textField: UITextField) {
    let textFieldRect : CGRect = self.view.window!.convertRect(textField.bounds, fromView: textField)
    let viewRect : CGRect = self.view.window!.convertRect(self.view.bounds, fromView: self.view)

    let midline : CGFloat = textFieldRect.origin.y + 0.5 * textFieldRect.size.height
    let numerator : CGFloat = midline - viewRect.origin.y - MoveKeyboard.MINIMUM_SCROLL_FRACTION * viewRect.size.height
    let denominator : CGFloat = (MoveKeyboard.MAXIMUM_SCROLL_FRACTION - MoveKeyboard.MINIMUM_SCROLL_FRACTION) * viewRect.size.height
    var heightFraction : CGFloat = numerator / denominator

    if heightFraction < 0.0 {
        heightFraction = 0.0
    } else if heightFraction > 1.0 {
        heightFraction = 1.0
    }

    let orientation : UIInterfaceOrientation = UIApplication.sharedApplication().statusBarOrientation
    if (orientation == UIInterfaceOrientation.Portrait || orientation == UIInterfaceOrientation.PortraitUpsideDown) {
        animateDistance = floor(MoveKeyboard.PORTRAIT_KEYBOARD_HEIGHT * heightFraction)
    } else {
        animateDistance = floor(MoveKeyboard.LANDSCAPE_KEYBOARD_HEIGHT * heightFraction)
    }

    var viewFrame : CGRect = self.view.frame
    viewFrame.origin.y -= animateDistance

    UIView.beginAnimations(nil, context: nil)
    UIView.setAnimationBeginsFromCurrentState(true)
    UIView.setAnimationDuration(NSTimeInterval(MoveKeyboard.KEYBOARD_ANIMATION_DURATION))

    self.view.frame = viewFrame

    UIView.commitAnimations()
}


func textFieldDidEndEditing(textField: UITextField) {
    var viewFrame : CGRect = self.view.frame
    viewFrame.origin.y += animateDistance

    UIView.beginAnimations(nil, context: nil)
    UIView.setAnimationBeginsFromCurrentState(true)

    UIView.setAnimationDuration(NSTimeInterval(MoveKeyboard.KEYBOARD_ANIMATION_DURATION))

    self.view.frame = viewFrame

    UIView.commitAnimations()

}

最后，因为我们使用委托方法

func textFieldShouldReturn(textField: UITextField) -> Bool {
        textField.resignFirstResponder()
        return true
    }

使用objective-c重构http://www.cocoawithlove.com/2008/10/sliding-uitextfields-around-to-avoid.html