UINavigationBar setBackgroundImage: forBarMetrics: Not Working - objective-c

Question

I just switched over to iOS 5 and everything appears to be working in my application aside from the custom navigation bar. I looked around and followed everybody's suggestion of calling the new methods setBackgroundImage: forBarMetrics: however it doesn't appear to work. This is the code I've tried to place both within the app delegate and within the viewDidLoad method of some of the view controllers:
UINavigationBar *nb = [[UINavigationBar alloc]init];
if( [nb respondsToSelector:#selector(setBackgroundImage:forBarMetrics:)] )
{
UIImage *image = [UIImage imageNamed:#"navBarBackground.png"];
[nb setBackgroundImage:image forBarMetrics:UIBarMetricsDefault];
}
[nb release];
Unfortunately this doesn't work. If anybody has any suggestions at all, I'm all ears!

Answer 1

To apply image to all your navigation bars, use the appearance proxy:
[[UINavigationBar appearance] setBackgroundImage:image forBarMetrics:UIBarMetricsDefault];
For an individual bar:
// Assuming "self" is a view controller pushed on to a UINavigationController stack
[self.navigationController.navigationBar setBackgroundImage:image forBarMetrics:UIBarMetricsDefault];
In your example, the background image won't change because nb isn't hooked up to anything.

Answer 2

Answer by rob is correct but if application runs on iOS 4.3 or lower app will crash. So you can implement this like
if([[UINavigationBar class] respondsToSelector:#selector(appearance)]) //iOS >=5.0
{
[[UINavigationBar appearance] setBackgroundImage:[UIImage imageNamed:#"navigationBar.png"] forBarMetrics:UIBarMetricsDefault];
[[UINavigationBar appearance] setBackgroundImage:[UIImage imageNamed:#"navBar-Landscape.png"] forBarMetrics:UIBarMetricsLandscapePhone];
}
This will set image for both mode Landscape and Portrait

Answer 3

You need to get the navigation bar from a navigation controller. Right now you are just creating one and then it deallocs when you release it. You need to get the navigation controller for your view controller.
UINavigationController * navigationController = [self navigationController];
UINavigationBar * nb = [navigationController navigationBar];

Answer 4

Note that if you want to apply the same to a toolbar, it is slightly different. Here's an example, building on Rob's answer:
[[UIToolbar appearance] setBackgroundImage:[UIImage imageNamed:#"NavBarDarkWoodGrain.png"] forToolbarPosition:UIToolbarPositionBottom barMetrics:UIBarMetricsDefault];

Answer 5

You didn't do something like use a UINavigationBar subclass? If you do this and override drawRect: on iOS5 and above, things will break.
See my answer here for a way to support both OS versions.

Answer 6

This worked for me.
UIView *parentViewLeft = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 320, 44)];
parentViewLeft.backgroundColor = [UIColor clearColor];
if ([self.navigationController.navigationBar respondsToSelector:#selector(setBackgroundImage:forBarMetrics:)]) {
[self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:#"navbar.png"]
forBarMetrics:UIBarMetricsDefault];
} else {
UIImageView* imgBG = [[UIImageView alloc]init];
imgBG.image = [UIImage imageNamed:#"navbar.png"];
imgBG.frame = CGRectMake(-10,0, 330, 44);
[parentViewLeft addSubview:imgBG];
}
UIBarButtonItem *customBarButtomLeft = [[UIBarButtonItem alloc] initWithCustomView:parentViewLeft];
self.navigationItem.leftBarButtonItem = customBarButtomLeft;