Question

I have achieved this but I am asking more if I did this right. I have been immersed in the apple documentation and iOS programming books. Since then I have fully reworked my app for reusability and all that good stuff.

Now I have a main UIViewController named RootController that handles a UINavigationController and a custom MenuController. I decided that UIViewController containment was the best approach for my RootController.

RootController ---> UINavigationController
               ---> MenuController

Now a problem occurred where I needed some of the sub UIViewControllers in the UINavigationController to communicate with the main RootController.

RootController ---> UINavigationController --> UIViewController
       ^_____________________________________________|

What I decided to do was extend UIViewController with a category.

UIViewController+RootController.h

@interface UIViewController (RootController)

@property (nonatomic, readonly) RootController *rootController;

@end

UIViewController+RootController.m

@implementation UIViewController (RootController)

- (RootController *)rootController {
    static RootController *rootControler;
    if(rootControler == nil) {
        UIViewController *vc = self;
        while((vc = vc.parentViewController)) {
            if([vc isMemberOfClass:[RootController class]]){
                rootControler = (RootController *)vc;
                break;
            }
        }
    }
    return rootControler;
}

@end

When [self rootController] is called by any UIViewController it will loop through the parent view controllers until it find one that matches RootController, it will then return the match. I also made the property static so it was only looked up once.

So my question is was this the right approach I made? I was trying to make something similar to UIViewController’s navigationController method.

I need access to the main root controller so I can handle the MenuController from any view within my app.

Answer 1

Your solution seems correct but not so clean imho.
In similar situations I usually prefer to obtain a reference in “inverse” method, using the AppDelegate.

For Example:

#import "AppDelegate.h" // at the top of your file

UIViewController *vc = [[(AppDelegate *)[[UIApplication sharedApplication] delegate] window] rootViewController]:

vc is a reference to your root view controller.
Take care because the root view controller of the window can change (if you change it :-). So, in this case, you should change your aproach (for example adding a @property to your AppDelegate and make your RootController setting this property on load)