How to add a button to UINavigationBar?

Question

How to add a button to UINavigationBar programmatically?

Answer 1

In Swift 2, you would do:

let rightButton: UIBarButtonItem = UIBarButtonItem(title: "Done", style: UIBarButtonItemStyle.Done, target: nil, action: nil)
self.navigationItem.rightBarButtonItem = rightButton

(Not a major change) In Swift 4/5, it will be:

let rightButton: UIBarButtonItem = UIBarButtonItem(title: "Done", style: UIBarButtonItem.Style.done, target: nil, action: nil)
self.navigationItem.rightBarButtonItem = rightButton