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

Now, an UIWindow has also a rootViewController property. When running the previous snippet of code, does that property gets populated with the rvcController or do I have to set it explicity?

You have to set it explicitly, and if you do, you can remove the addSubview line, because that's handled automatically when you set a root view controller.

Then, in a UINavigationController it is possible to set a RVC that is different from the previous RVC set for the entry point.

Of course, a navigation controller's root view controller has nothing to do with that of the window.

In this case, the first time I add a controller to the navigationController stack (pushing a new controller on it), does the framework set that controller as the RVC for the navigationController or do I have to set it explicity through initWithRootViewController method?

initWithRootViewController is just a shortcut for initializing an empty navigation controller and pushing the first (root) view controller onto the stack. Note that rootViewController is not a property of UINavigationController, you would access it via [navController.viewControllers objectAtIndex:0].