UINavigationBar setBackgroundImage: forBarMetrics: Not Working

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];

Unfortuna开发者_JAVA技巧tely this doesn't work. If anybody has any suggestions at all, I'm all ears!

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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.

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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

---

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];

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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];

---

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.

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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;