title: Delay in UINavigationBar Appearance Effect
body: <p><a href="https://i.stack.imgur.com/ypFhm.gif" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ypFhm.gif" alt="Gif of the effect"></a></p>
  
  <p>Background: my app uses Firebase as a backend, listens for state changes to the current user, and, when logged in, sets the above controller as the root view controller. It is a <strong><code>UITabBarController</code> that contains several <code>UINavigationControllers</code></strong>. Well before it is presented, I style the navigation bar via <code>UINavigationBar.appearance()</code>. I notice two things from the loading behavior:</p>
  
  <ul>
  <li>The bar loads after the contained content.</li>
  <li>You can see the dividing line that would appear from an un-styled navigation bar, which leads me to believe that the default appearance has some sort of delay.</li>
  </ul>
  
  <p>Has anyone experienced something like this? My goal is to have the controller fully load at once, and ideally not see the divider line.</p>
  
  <pre><code>func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -&gt; Bool {
      Appearance.shared.configure() // All UINavigationBar-related styling
  
      window = UIWindow(frame: UIScreen.mainScreen().bounds)
      window?.backgroundColor = UIColor.whiteColor()
      window?.rootViewController = UIViewController()
      window?.makeKeyAndVisible()
  
      configureFirebase() // Listens for FIRAuth change, then sets window.rootViewController = MyTabBarController()
      return true
  }
  </code></pre>