Refresh ViewController after PresentedController is dismissed

When my app starts up i create a 2 view controllers. One for my main landing and one for login, which is only shown if the user has not logged in before.

What I need to do is refresh the look of the landing page controller after I dismiss the login controller.

This is the code snippet to launch the two controllers:

// create a new window instance based on the screen size window = new UIWindow (UIScreen.MainScreen.Bounds);

            mainAppNavController = new UINavigationController();
            window.RootViewController = mainAppNavController;
            homeController = new LockerViewController ();
            mainAppNavController.PushViewController ( homeController, false );

            // make the window visible
            window.MakeKeyAndVisible ();

            var login = new LoginViewController ();
            mainAppNavController.PresentViewController (login, false, null);

Then once the login is complete, I dismiss it with

//get rid of the login window
                DismissViewController (true, null);

How do I catch the fact that the login window has been dismissed so I can refresh the underlying landing page view controller?

Thanks for any help!!