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

in AppDelegate.m

(BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:UIScreen.mainScreen.bounds];



    UIViewController *viewController = // determine the initial view controller here and instantiate it with [storyboard instantiateViewControllerWithIdentifier:];

    self.window.rootViewController = viewController;//making a view to root view
    [self.window makeKeyAndVisible];

    return YES;
}