Background Image for UINavigationcontroller

Try this

[self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:@"yourImage"] forBarMetrics:UIBarMetricsDefault];

Use this

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    [self.window makeKeyAndVisible];
    [self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:@"yourImage"] forBarMetrics:UIBarMetricsDefault];
    return YES;
}