How do I programmatically add a view right under the navigation bar?

Question

I\'m trying to add a view to a UINavigationController with its top aligned with the navigation bar\'s bottom.

I tried using constraints by adding the follo

Answer 1

override func viewDidAppear(_ animated: Bool) {
let label = UILabel(frame: CGRect(x: 0, y: (navigationController?.navigationBar.frame.height)! + 20, width: UIScreen.main.bounds.width, height: 40))
label.translatesAutoresizingMaskIntoConstraints = true
label.text = "Hello"
label.backgroundColor = UIColor.red
self.view.addSubview(label)

}