How to set root view controller

Question

I set up an empty app with only an app delegate class, then subclassed a view controller class to create a xib to layout the app and make connections.

But when I tried

Answer 1

You need to set 2 things for that..

1. in AppDelegate.m file: _applicationDidFinishLaunchingWithOptions_

   self.window.rootViewController = self.viewController;

2. in application.m

   retVal = UIApplicationMain(argc, argv, nil, @"AppDelegate");