How to trigger viewWillAppear when going back in the navigation controller hierarchy?

Question

I've been trying various methods to trigger some code when returning to the first level of a UINavigationController, but none of the below work...

// HomeViewController.m
-(void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    NSLog(@"trigger 1");
}

- (void)viewWillAppear:(BOOL)animated {
    NSLog(@"trigger 2");
}

-(void) viewDidAppear:(BOOL)animated {
    NSLog(@"trigger 3");
}

I'm starting to think I've set up my app wrong.. is it something about having UIViewControllers within UIViewControllers?

This is the nib for the app.. it's a UITabBarController with a navigation controller for each tab, and within that the first page of the UINavigationController. Is this setup the reason why the methods are not triggering?

Not shown in this is a UIView at the bottom which is linked to the File Owner's view. And to make it more complicated, MainViewController is actually the flip side of a Utility-style app.

Answer 1

Just to say I solved this another way. I needed to call something like viewWillAppear because I needed to update my first view table when something had changed in my second view.

The way I achieved it was, in my 'tableView: commitEditingStyle' method (called after I delete something), I put this at the end..

[[[[self.navigationController.tabBarController.viewControllers objectAtIndex:0] viewControllers] objectAtIndex:0] reloadTheTable];

reloadTheTable is a method in my HomeViewController which does stuff like update arrays and [tableView reloadData] etc;

That's a lot of brackets. I'm sure my nib can be set up to make that simpler. I think Kasparov has said that he thinks four moves ahead... and four brackets is my limit.

I worked it out by doing things like this:

NSString *name = NSStringFromClass ([[self parentViewController] class]);
NSLog(@"%@", name); // outputs UINavigationController

and slowly adding to it until I found what I was looking for:

name = NSStringFromClass ([[[[self.navigationController.tabBarController.viewControllers objectAtIndex:0] viewControllers] objectAtIndex:0] class]); //UINavigationController
NSLog(@"%@", name); // outputs HomeViewController

There is something definitely odd in the way viewWillAppear gets cancelled when you puts views within views.