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)
        }
}

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。

如果你正在使用自动布局，我假设你已经设置了底部空间为Superview约束。如果是这种情况，您只需更新约束的值。这是你如何用一点动画来做到这一点。

func keyboardWasShown(notification: NSNotification) {
    let info = notification.userInfo!
    let keyboardFrame: CGRect = (info[UIKeyboardFrameEndUserInfoKey] as! NSValue).CGRectValue()

    UIView.animateWithDuration(0.1, animations: { () -> Void in
        self.bottomConstraint.constant = keyboardFrame.size.height + 20
    })
}

添加硬编码的20只是为了将文本框弹出到键盘上方一点。否则键盘的上边距和文本框的下边距将会接触。

当键盘关闭时，将约束的值重置为原始值。

在现有的答案上有一些改进。

首先，uikeyboardwillchangeframeotification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，使用第三方键盘等)和旋转(但注意下面的评论表明键盘将隐藏也应该处理以支持硬件键盘连接)。

其次，动画参数可以从通知中提取，以确保动画正确地组合在一起。

可能有一些选项可以进一步清理此代码，特别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)
   }
}

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
}

}

我的做法如下:

class SignInController: UIViewController , UITextFieldDelegate {

@IBOutlet weak var scrollView: UIScrollView!

// outlet declartion
@IBOutlet weak var signInTextView: UITextField!

var kbHeight: CGFloat!

/**
*
* @method viewDidLoad
*
*/

override func viewDidLoad() {
    super.viewDidLoad()

    self.signInTextView.delegate = self

}// end viewDidLoad

/**
*
* @method viewWillAppear
*
*/

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

    NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillShow:"), name: UIKeyboardWillShowNotification, object: nil)

    NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillHide:"), name: UIKeyboardWillHideNotification, object: nil)

}// end viewWillAppear

/**
*
* @method viewDidAppear
*
*/

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


}// end viewDidAppear

/**
*
* @method viewWillDisappear
*
*/
override func viewWillDisappear(animated: Bool) {
    super.viewWillDisappear(animated)
    NSNotificationCenter.defaultCenter().removeObserver(self)
}

/**
*
* @method textFieldShouldReturn
* retun the keyboard value
*
*/

// MARK -
func textFieldShouldReturn(textField: UITextField) -> Bool {
    signInTextView.resignFirstResponder()
    return true;

}// end textFieldShouldReturn

// MARK - keyboardWillShow
func keyboardWillShow(notification: NSNotification) {
    if let userInfo = notification.userInfo {
        if let keyboardSize =  (userInfo[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue() {
            kbHeight = keyboardSize.height
            self.animateTextField(true)
        }
    }
}// end keyboardWillShow

// MARK - keyboardWillHide
func keyboardWillHide(notification: NSNotification) {
    self.animateTextField(false)
}// end keyboardWillHide

// MARK - animateTextField
func animateTextField(up: Bool) {
    var movement = (up ? -kbHeight : kbHeight)

    UIView.animateWithDuration(0.3, animations: {
        self.view.frame = CGRectOffset(self.view.frame, 0, movement)
    })
}// end animateTextField

/**
*
* @method didReceiveMemoryWarning
*
*/

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.

}// end didReceiveMemoryWarning


}// end SignInController