Update button constraint by keyboard open and close

Keyboard View Resize

override func viewDidLoad() {
    super.viewDidLoad()
    NotificationCenter.default.addObserver(self, selector: #selector(keyboardNotification(notification:)), name: UIResponder.keyboardWillChangeFrameNotification, object: nil)
}

@objc func keyboardNotification(notification: NSNotification) {
    if let userInfo = notification.userInfo {
        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 {
            keyboardHeightLayoutConstraint?.constant = 8
        } else {
            keyboardHeightLayoutConstraint?.constant = (endFrame?.size.height ?? 0.0) + 8
        }
        UIView.animate(withDuration: duration,
                                   delay: TimeInterval(0),
                                   options: animationCurve,
                                   animations: { self.view.layoutIfNeeded() },
                                   completion: nil)
    }
}