Why isn't viewWillDisappear or viewDidAppear being called?

Question

I have a UINavigationController with a UITableView as my main menu. User clicks on a cell and a new view is pushed on the stack. In one case I push another UITableView that needs a toolbar. So on that 2nd tableView's init I setup the self.toolbarItems property with the correct items. But then I need to call [self.navigationController setToolbarHidden:NO animated:YES]; So it makes sense to call this in the viewDidAppear or viewWillAppear method. But I put it in those methods and find out (Also via NSLog) that they never get called. The same goes for hiding it in viewWillDisappear or viewDidDisappear. Why don't these methods get called? Where should I be doing this hiding/showing of the toolbar then?

Answer 1

I have noticed behavior where if a parent controller (like UINavigationController or UITabBarController) never get's viewWill/DidAppear called on it, it won't call it on the child controllers either. So make sure that in the code where you create the parent controller, you call viewWillAppear, show it, then call viewDidAppear. Then it should make those calls on it's child controllers as is appropriate.

Double check the parent controller is having those methods called, and call them yourself if they are not.

Answer 2

Yes Its true

you can do this by first write this code in

- (void)viewDidLoad {
    self.navigationController.delegate = self;  
}

And then write the code which you want to write in viewWillAppear

- (void)navigationController:(UINavigationController  *)navigationController didShowViewController:(UIViewController  *)viewController animated:(BOOL)animated {

    if ([viewController isKindOfClass:[self class]]) {
        //write your code here
    } 
}

Answer 3

Although you solved your problem, in case someone comes along in the future another problem could have been that you forgot the animated: argument to either method - that is to say, the format of the method needs to look like:

- (void) viewWillAppear:(BOOL)animated