viewWillAppear, viewDidAppear not being called, not firing

Question

(This is both question and answer since it took quite a bit of digging to find the real answer.)

Symptom: viewWillAppear, viewDidAppear were not being called in my UIViewController.

Cause: Embedding a UINavigationController or UITabBarController (my case) in a UIViewController somehow interrupts with the calling of these methods.

Solution: Call them manually in the UIViewController that contains the aforementioned UINavigationController / UITabBarController.

For example (assuming projectNavigationController is your UINavigationController):

-(void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    [projectNavigationController viewWillAppear:animated];
}

-(void)viewWillDisappear:(BOOL)animated { 
    [super viewWillDisappear:animated];
    [projectNavigationController viewWillDisappear:animated];
}

-(void)viewDidAppear:(BOOL)animated { 
    [super viewDidAppear:animated];
    [projectNavigationController viewDidAppear:animated];
}

-(void)viewDidDisappear:(BOOL)animated { 
    [super viewDidDisappear:animated];
    [projectNavigationController viewDidDisappear:animated];
}

In my case I had an inner UITabBarController and I called the methods accordingly and all was solved.

(Attribution on the solution: http://davidebenini.it/2009/01/03/viewwillappear-not-being-called-inside-a-uinavigationcontroller/)

Answer 1

Your fix is a workaround for your bad code. You are not supposed to 'embed' view controllers in other view controllers.

If you do, for example if you were writing your own tabbarcontroller-like view controller, then you should add the views of your 'sub-viewcontroller' to the window and not as subviews of the root uiviewcontroller.

If you add them to the window then the system will actually also send your view controller the right callbacks.