title: Proper Technique of sigining in with a Login Screen and TabController
body: <p>i created the login screen of my app has the rootview controller in my AppDelegate.swift file. But i also created a TabController as entry point to the app using storyboards. After several thoughts into it, i came across a solution and wanted to know if this is the right approach. I want the tabController to be the rootview controller of the app. But the tabController should be only displayed if the user is logged in. If the user isn't logged in then call the login screen which is a navgiation controller that allows the user to be sign in or sign up with the app. It recieves a token from the server and segues to the tabController. If the user has a token the default screen is the tabcontroller if not call the login screen. I want to know if my approach is the right way?</p>
  
  <p>For now in my Appdelegate.swift file i defined the login screen called WelcomeHomeController.swift as the login screen but i don't want the rootviewcontroller to be the default screen. Also should i be defining the rootViewController in AppDelegate.swift class?</p>
  
  <pre><code>func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -&gt; Bool {
  
          let welcomeHomeController:UIViewController = WelcomeHomeController(nibName: nil, bundle: nil)
          welcomeHomeController.view.backgroundColor = UIColor.whiteColor()
          let navController:UINavigationController = UINavigationController(rootViewController: welcomeHomeController)
  
          //create window
          self.window = UIWindow(frame: UIScreen.mainScreen().bounds)
          self.window?.backgroundColor = UIColor.darkGrayColor()
          self.window?.rootViewController = navController
          self.window!.makeKeyAndVisible()
  }  
  </code></pre>
  
  <p>I wanted some help or an example of how to accomplish this. </p>