Adding Done Button to Keyboard

In this example I use a UIToolBar to contain the done button but you can use any UIView to assign to inputAccessoryView.

 
class ViewController: UIViewController {

    @IBOutlet weak var nameTextField: UITextField!
    @IBOutlet weak var phoneNumberTextField: UITextField!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let keyboardToolBar = UIToolbar()
        keyboardToolBar.sizeToFit()
        
        let flexibleSpace = UIBarButtonItem(barButtonSystemItem: 
            UIBarButtonSystemItem.flexibleSpace, target: nil, action: nil)
        let doneButton = UIBarButtonItem(barButtonSystemItem: 
            UIBarButtonSystemItem.done, target: self, action: #selector(self.doneClicked) )
        
        keyboardToolBar.setItems([flexibleSpace, doneButton], animated: true)
        
        nameTextField.inputAccessoryView = keyboardToolBar
        phoneNumberTextField.inputAccessoryView = keyboardToolBar
    }

    func doneClicked() {
        view.endEditing(true)
    }
}
 

Here is an example of using a Navigation Bar:

 
let navItem = UINavigationItem()
let doneBtn = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.done, 
    target: self, action: #selector(self.doneClicked))
navItem.rightBarButtonItem = doneBtn

let navBar = UINavigationBar(frame: CGRect(x: 0, y: 0, width: view.frame.width, 
    height: 44))
navBar.pushItem(navItem, animated: true)

nameTextField.inputAccessoryView = navBar
phoneNumberTextField.inputAccessoryView = navBar
 

(Xcode 8, Swift 3.0)