Reset UINavigationController to first controller when tab bar is clicked

Question

My application has 3 tab bar items, each mapped to a separate view controller. My problem is the first controller is a UINavigation controller, and it drills-down about 3 levels deep. I don't have any problems with the navigation, but when I click on a different tab bar item and then when I return to the first tab bar item (the one with the UINav controller), I'd prefer it to reset back to the first controller in the nav sequence.

I read that you have to do something like:

- (void)tabBar:(UITabBar *)tabBar didSelectItem:(UITabBarItem *)item
{
    [[self navigationController] popViewControllerAnimated:NO];
}

But I'm not sure where I should put this method. Who is the delegate for the tab bar controller? It's setup in AppDelegate... should it go in there?

Thanks.

Answer 1

Sure, in your AppDelegate when you are creating the UITabBarController you can set the tab bar controller's delegate to be self (i.e. the AppDelegate). Then you can put the tabBar:didSelectItem: method in your AppDelegate and it should be called whenever the user taps a UITabBarItem. I would create an instance variable property in your AppDelegate and keep a reference to the UITabBarItem which is used for the Nav controller tab (Let's call it tabBarItemForNavControllerTab). You should also have a reference to the nav controller that lives in that first tab so that you can control it from the AppDelegate (Let's call it navControllerInFirstTab)

- (void)tabBar:(UITabBar *)tabBar didSelectItem:(UITabBarItem *)item
{
    if (item != self.tabBarItemForNavControllerTab) {
        [self.navControllerInFirstTab popToRootViewControllerAnimated:NO];
    }
}

You can use popToRootViewControllerAnimated: on the UINavigationController instead of popping each one off the stack individually.

Answer 2

You need to set yourself as the delegate for the tabBar and implement – tabBar:didSelectItem: the you ask the navigation controller for its views [[self navigationController ] viewControllers] which returns an NSArray of UIViewControllers, then pop each view controller in the array until you get to the root view.

http://developer.apple.com/library/ios/#documentation/uikit/reference/UITabBarDelegate_Protocol/Reference/Reference.html