I've created a custom keyboard and implemented the: class KeyboardViewController: UIInputViewController The imlementation looks like this: override func viewDidLoad() { super.viewDidLoad() var stack = UIStackView() stack.axis = .vertical stack.spacing = 8 stack.translatesAutoresizingMaskIntoConstraints = false stack.distribution = .fill stack.heightAnchor.constraint(equalToConstant: 200).isActive = true .... view.addSubview(stack) NSLayoutConstraint.activate([ stack.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 20), stack.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -20), stack.topAnchor.constraint(equalTo: view.topAnchor, constant: 10), stack.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -10) ]) The problem is that the keyboard seems to start showing in the size (I've printed the parent frame): Optional(<UIView: 0x101008480; frame = (0 0; 390 844); autoresize = W+H; layer = <CALayer: 0x600000207b80>>) and than resizes to my given height. But it's not fast enough so that I can see some glitches whenever I switch from another keyboard to my custom keyboard. Is there a way to prevent this resizing or start the keyboard in a given size? This is just not the best user experience.