Everything is much easier in Swift 3.0 Xcode 8
Using the code below in App Delegate file, after
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
insert this:
UINavigationBar.appearance().barStyle = .black
UINavigationBar.appearance().barTintColor = UIColor(red: 230, green: 32, blue: 31, alpha: 1.0)