Create NavBar programmatically with Button and Title Swift

Basically azimov's answer in Swift 4

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)
}

@objc func done() { // remove @objc for Swift 3

}

Updated for Swift 5

Create a navigation item instance and set title and right/left buttons to it. After navigation item is configured add it to the navigation bar.

let navBar = UINavigationBar(frame: CGRect(x: 0, y: 0, width: view.frame.size.width, height: 44))
view.addSubview(navBar)

let navItem = UINavigationItem(title: "SomeTitle")
let doneItem = UIBarButtonItem(barButtonSystemItem: .done, target: nil, action: #selector(selectorName:))
navItem.rightBarButtonItem = doneItem

navBar.setItems([navItem], animated: false)