Setting Navigation Bar Colour

AppDelegate.swift

class AppDelegate: UIResponder, UIApplicationDelegate {

  func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

    // Any other set-up code you need.

    // This allows us to access the navigation bar since .appearance returns the proxy for the receiver,
    // our UINavigationBar.
    let navigationBarAppearace = UINavigationBar.appearance()
    // This colour applies to the navigation items and bar button items.
    navigationBarAppearace.tintColor = .blue
    // This colour applies to the navigation bar background.
    navigationBarAppearace.barTintColor = .white
    // This is THE big one. This indicates whether the bar background is translucent or not.
    // By indicating false here, we are able to ensure the barTintColor assigned above is
    // the full colour we intend.
    navigationBarAppearace.isTranslucent = false
    // This colour applies to the title of the view controller pushed into the stack.
    navigationBarAppearace.titleTextAttributes = [NSAttributedString.Key.foregroundColor: UIColor.blue]

    // Override point for customization after application launch.
    return true
  }
}