You change the title by changing the title of the view controller being displayed:
viewController.title = "some title"
Normally this is done in view did load on the view controller:
override func viewDidLoad() {
super.viewDidLoad()
self.title = "some title"
}
However, this only works if you have your view controller embedded in a UINavigationController. I highly recommend doing this instead of creating a navigation bar yourself. If you insist on creating a navigation bar yourself, you can change the title by doing:
navigationBar.topItem.title = "some title"