Programming iOS: clarifications about Root View Controller

Question

Through this question I would like to know if I understand well the notion of Root View Controller.

In iOS application, the Root View Controller (RVC) is the control

Answer 1

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

// Override point for customization after application launch.
   self.window.backgroundColor = [UIColor whiteColor];

   ViewController *viewcontroller =[[ViewController alloc]initWithNibName:@"ViewController" bundle:nil];

self.window.rootViewController= viewcontroller;




 [self.window makeKeyAndVisible];
 return YES;

}