override func viewDidLoad() {
    super.viewDidLoad()
    self.setNavigationBar()
}

func setNavigationBar() {
    let screenSize: CGRect = UIScreen.main.bounds
    let navBar = UINavigationBar(frame: CGRect(x: 0, y: 0, width: screenSize.width, height: 44))
    let navItem = UINavigationItem(title: "")
    let doneItem = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.done, target: nil, action: #selector(done))
    navItem.rightBarButtonItem = doneItem
    navBar.setItems([navItem], animated: false)
    self.view.addSubview(navBar)
}

func done() {
print("done")
}