Show UIView above keyboard not working properly

Question

I'm trying to move the constraintToBottom.constant of a UIView where my UITextField is located above the keyboard once it's shown. I set the Notification observer, but for some reason it's not working.

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: Notification) {
    if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
        UIView.animate(withDuration: 0.3, animations: {
            self.constraintToBottom.constant = keyboardSize.height
            print("constant", self.constraintToBottom.constant)
        })
    }
}

When I print the constraintToBottom.constant it shows:

constant 346.0

And yet, the UIView is still not visible above the keyboard as usual. What am I doing wrong?

UPDATE

As suggested, the minus does the trick BUT there's also extra space and it looks like this:

Answer 1

You need to re-layout the view

self.constraintToBottom.constant = -1 * keyboardSize.height
UIView.animate(withDuration: 0.3, animations: {
     self.view.layoutIfNeeded()
     print("constant", self.constraintToBottom.constant)
})