hi,
Is there a way to find out whether the back button (Navigation bar) is clicked for a particular view ? if yes how ?
A:
First of all, I didn't try this myself. I don't know of a way to intercept the click on the button. What "might" work is the following: There is the UINavigationBarDelegate, which contains the navigationBar:shouldPopItem: event. This event is called before a navigationItem is removed from the stack of your navigationBar, so if you handle this event, you might be able to do whatever you want to archive.
Phlibbo
2010-09-22 13:28:16
The OP doesn't state whether they're using a navigation controller or not. If not, Phlibbo's suggestion is a good one; however, if there's a nav controller involved then I don't think hooking into the nav bar delegate is a good idea since it will probably break the nav controller. In that case, a possible option would be to use the navigationController:willShowViewController:animated: method in UINavigationControllerDelegate.
Echelon
2010-09-22 14:25:12
A:
"handling events before" suggests you want to clean up or save state before the user leaves the view. In that case, I'd use viewWillDisappear: or viewDidDisappear:. If you need to distinguish between navigating back and navigating "forwards" (e.g. pushing a VC, or presenting a modal VC), you might be able to do something like:
-(void)viewDidDisappear:(BOOL)animated
{
if (!self.parentViewController)
{
// back button pressed/modal VC dismissed/etc, hopefully
}
}
I haven't tested this, but my understanding is that "Will"-methods are called before the VC hierarchy is changed, and "Did"-methods are called afterwards.
If you're saving state, you should also handle UIApplicationWillEnterBackgroundNotification.
tc.
2010-09-23 02:00:39