How do I integrate popToRootViewControllerAnimated with my tabs?

Question

I am trying to make one of my tab buttons go to the root using popToRootViewControllerAnimated. My question is: where do I put this code for it to work? I have my tabs created through Interface Builder... do they have to be hard coded for this to work?

Here is the code that I'm looking to use:

[self.navigationController popToRootViewControllerAnimated:YES];

New code in AppDelegate:

- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController {
    if (viewController = HomeViewController) {
        [HomeViewController popToRootViewControllerAnimated:NO];
    }
}

Answer 1

Adam - I ended up ditching the subclass idea even though it worked, as there is a much easier method.

- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController {
    if ([viewController isKindOfClass:[UINavigationController class]]) {
        [(UINavigationController*)viewController popToRootViewControllerAnimated:YES];
    }
}

This is the code required. I've uploaded this sample project to play around with. The main points are

• the UITabBarController delegate must be set to the App Delegate.
• the App Delegate must implement the <UITabBarControllerDelegate> protocol.
• the App Delegate must implement the code above.

The sample project also shows one way to selectively choose which navigation controllers this occurs with.

Answer 2

Yes this needs to be hardcoded.

If you're using a UITabBarController (I assume you probably are) you'll need to subclass it and override. This will try pop to the root view controller of each navigation controller on a tab. If the root view of a tab item is not a navigation item you will get an exception though.

@interface MyTabBarControllerSubClass : UITabBarController {
}
@end
@implementation MyTabBarControllerSubClass
- (void)tabBar:(UITabBar *)tabBar didSelectItem:(UITabBarItem *)item {
    [super tabBar:tabBar didSelectItem:item];
    [(UINavigationController*)self.selectedViewController popToRootViewControllerAnimated:YES];
}
@end

Don't forget to select your subclass in IB :-)

You could also make something a UITabBarControllerDelegate. Though it would probably be harder to implement.

Answer 3

Not sure why, but for me on Xcode 6 with Swift this solution did not work out. It seems even if didSelectViewController is called, popToRootViewControllerAnimated(false) is not.

I found that calling shouldSelectViewController instead works fine for me:

func tabBarController(tabBarController: UITabBarController, shouldSelectViewController viewController: UIViewController) -> Bool {
    if viewController.isKindOfClass(UINavigationController) {
        (viewController as UINavigationController).popToRootViewControllerAnimated(false)
        return true
    }
    return true
}

Not sure though if it is a good approach.