UINavigationBar jumping up when app becomes active - iphone

Question

I have a custom UINavigationBar that has a different image background and height than the default one. It's displayed normally but as soon as I go back and forth between apps the background image and buttons inside the navigation bar jump up.
The UINavigationBar is created in a nib and has a custom class that overrides the default implementation to add the image:
#implementation MyUINavigationBar
- (void)drawRect:(CGRect)rect {
UIImage *image = [UIImage imageNamed: #"nav.png"];
rect.size.height = 60;
[image drawInRect:rect];
}
#end
At this point the bar isn't displayed correctly. In - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions of my app delegate I fix this with this code:
self.navigationController.view.frame = CGRectMake(0, 20, 320, 460);
self.navigationController.navigationBar.frame = CGRectMake(0, 0, 320, 60);
Now everything shows up correctly. When I switch to another app and go back again the bar jumps up, just as if the frames weren't applied. This happens right after I switch back to the app.
Below are two screenshots showing what's going on. The first one shows the correct version, the other one the faulty one.
Any idea what might be going on? I tried applying the new frames in viewWillAppear and viewDidAppear of the active view or in applicationDidBecomeActive of the app delegate but that didn't help.
https://skitch.com/instromaniac/rtagr/ios-simulator
https://skitch.com/instromaniac/rtaf9/view-not-ok

Answer 1

I spent days to figure this out, here is the trick that really work for a complete, customized backButton.
The backBarButtonItem is totally locked down in the iOS SDK (4.3 as far as I know), so we have to use a leftBarButtonItem that do the job in place of the regular back button.
Whereas the backBarButtonItem has to be defined in the Root View Controller of your UINavigationController, we have to setup our fake BackButton in the child view (ie. nextViewController in my example).
This code is in my Root View Controller (Which is a UITableViewDelegate), in -(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
[[self navigationController] pushViewController:nextViewController animated:YES];
here is the graal for displaying our fake back button in a 70px Custom UINavigationBar (Play with the frames to fit your needs) :
-(void)handleBack:(id)sender {
// Simulate the original back button
[self.navigationController popViewControllerAnimated:YES];
}
-(void)viewWillAppear:(BOOL)animated {
// Making a custom button
UIButton *backBtn = [UIButton buttonWithType:UIButtonTypeCustom];
[backBtn setImage:[UIImage imageNamed:#"back-button.png"] forState:UIControlStateNormal];
[backBtn setImage:[UIImage imageNamed:#"back-button-hover.png"] forState:UIControlStateHighlighted];
[backBtn setImage:[UIImage imageNamed:#"back-button-disabled.png"] forState:UIControlStateDisabled];
[backBtn setFrame:CGRectMake(6, 4, 60, 30)];
// Binding custom target & action to the button
[backBtn addTarget:self action:#selector(handleBack:) forControlEvents:UIControlEventTouchUpInside];
// Nesting the button in a UIView to position the button anywhere!
UIView *backView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 60, 70)];
[backView addSubview:backBtn];
// Nesting all of these into a UIBarButtonItem
UIBarButtonItem *backItem = [[UIBarButtonItem alloc] initWithCustomView:backView];
// Overwrite original backbutton (self.navigationItem.backBarButtonItem DO NOT WORK HERE
self.navigationItem.leftBarButtonItem = backItem;
// Memory clean up
[backItem release];
[backView release];
}
Have fun ;)

Answer 2

Try changing the frame of the navigation controller's view as
self.navigationController.view.frame = CGRectMake(0,0,320,480);
Hope this helps