How do I change navigationBar font in Swift?

Try this:

self.navigationController.navigationBar.titleTextAttributes = [ NSFontAttributeName: UIFont(name: "CaviarDreams", size: 20)!]

Edit: Now, UIFont must be unwrapped to be able to be used here.

Swift 5 (+ safe handling of optional UIFont)

self.navigationController?.navigationBar.titleTextAttributes = [ NSAttributedString.Key.font: UIFont(name: "Caviar-Dreams", size: 20) ?? UIFont.systemFont(ofSize: 20)]

Using Swift, I added this to AppDelegate.swift in

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {        // Override point for customization after application launch.        UINavigationBar.appearance().titleTextAttributes = [            NSFontAttributeName: UIFont(name: "DINNextLTW04-Regular", size: 20)!        ]        return true    }

Hope it helps!

Swift 2.0:

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {        UINavigationBar.appearance().titleTextAttributes = [            NSFontAttributeName: UIFont(name: "Arial-Regular", size: 30)!        ]        return true    }

Or

 override func viewDidLoad() {  super.viewDidLoad()  self.navigationController?.navigationBarHidden =  false  self.title = "SAMPLE"//Set Color  let attributes: AnyObject = [ NSForegroundColorAttributeName: UIColor.redColor()]  self.navigationController!.navigationBar.titleTextAttributes = attributes as? [String : AnyObject]//Set Font Size  self.navigationController!.navigationBar.titleTextAttributes = [NSFontAttributeName: UIFont(name: "Arial", size: 37.0)!]; }