How to create backBarButtomItem with custom view for a UINavigationController

Question

I have a UINavigationController into which I push several views. Inside viewDidLoad for one of these views I want to set the self.navigationI

Answer 1

I too have been having problems with customView on a navigationItem.backBarButtonItem. I suspect it's probably just b0rked in the SDK.

While the workarounds outlined here do work, I've come up with a solution which is a little more elegant: it still uses navigationItem.leftBarButtonItem, but takes care of it for you automagically (no more need for 'child' view controllers to need to know anything about their 'parent' and/or to manually set navigationItem.leftBarButtonItem).

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First up, have some class be a UINavigationControllerDelegate for the UINavigationController whose back button you're interested in. Then, in this class, set up something like the following willShowViewController delegate method:

-(void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated{
    // reference to view controller stack
    NSArray *viewControllers = [ navigationController viewControllers ];
    if( [ viewControllers count ] > 1 ){
        // the view controller we'll be linking to
        UIViewController *backViewController = [ viewControllers objectAtIndex: [ viewControllers count ] - 2 ];
        // create custom UIBarButtonItem
        UIBarButtonItem *leftButton = [[ UIBarButtonItem alloc ] initWithCustomView: someCustomView ];
        // set it as the leftBarButtonItem on the incoming viewcontroller
        viewController.navigationItem.leftBarButtonItem = leftButton;
        // tidy up
        [ leftButton release ];
    }
}

I had some further problems with this; it seems that UIBarButtonItem.action and UIBarButtonItem.target don't work when it's a navigationItem.leftBarButtonItem. So, you're left with a custom back button that doesn't actually go back. I'll leave responding to touches in your custom view as an exercise for the reader (I used a UIButton), but you'll need add this method to your delegate class:

-(void)onDummyBackButtonTapped{
    [ someNavigationController popViewControllerAnimated: YES ];
}

and hook it up to fire when your custom view is tapped.