Move views out of the way when keyboard appears, Swift 4.1, using Auto-Layout / Interface Builder / Storyboard

AutoResizeViewControllerForKeyboard.swift

{
    // Move views when keyboard appears/disappears
    // Snipped from ViewController.swift
    
    // This constraint should be tied to the top superview or safe area in Storybaord
    @IBOutlet weak var closeButtonTopConstraint: NSLayoutConstraint!
    
    private var topConstraintOriginalConstant: CGFloat?
    private var topConstraintScrolledConstant: CGFloat = 0
    
    override func viewDidLoad() {
        super.viewDidLoad()

        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(_:)), name: .UIKeyboardWillShow, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(_:)), name: .UIKeyboardWillHide, object: nil)
    }
    
    @objc func keyboardWillShow(_ sender: NSNotification) {
        if topConstraintOriginalConstant == nil {
            topConstraintOriginalConstant = closeButtonTopConstraint.constant
            topConstraintScrolledConstant = topConstraintOriginalConstant! - 200
        }
        
        closeButtonTopConstraint.constant = topConstraintScrolledConstant
        UIViewPropertyAnimator(duration: 0.25, curve: .easeOut) {
            self.view.layoutIfNeeded()
        }.startAnimation()
    }
    
    @objc func keyboardWillHide(_ sender: NSNotification) {
        closeButtonTopConstraint.constant = topConstraintOriginalConstant ?? closeButtonTopConstraint.constant
        UIViewPropertyAnimator(duration: 0.25, curve: .easeOut) {
            self.view.layoutIfNeeded()
        }.startAnimation()
    }
}