I have noticed in some of my older apps that in situations where I have added a custom View Controller I have not changed the View Controller class in the application delegate. For example, below I have created a CustomViewController class but have declared viewController as UIViewController.

@interface ApplicationAppDelegate: NSObject <UIApplicationDelegate> {
    UIWindow *window;
    UIViewController *viewController;
}

My question is, both work, but for correctness should I be writing this as follows:

@class CustomViewController;
@interface ApplicationAppDelegate: NSObject <UIApplicationDelegate> {
    UIWindow *window;
    CustomViewController *viewController;
}

gary