SWIFT : Custom ViewController as InitialViewController

Go to AppDelegate.swift

var window: UIWindow?

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {

         self.window = UIWindow(frame: UIScreen.mainScreen().bounds)

        let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)

        let wViewController =        mainStoryboard.instantiateViewControllerWithIdentifier("ViewController") as? ViewController

       self.window?.rootViewController = wViewController

       self.window?.makeKeyAndVisible()

       return true

}