Quick way to modify look of UITabBarController

YourUtilAppDelegate.m

#pragma mark UITabBarController customisation to add background image
//In your appDelegate, just use categories to add functionality to UITabBarController
//overloading viewDidLoad. No need to subclass
@implementation UITabBarController (UITabBarControllerCategory)

- (void)viewDidLoad {
    [super viewDidLoad];
    
    CGRect frame = CGRectMake(0.0, 0.0, self.view.bounds.size.width, 48);
    UIImageView *imageView = [[UIImageView alloc] initWithFrame:frame];
    UIImage *img  = [UIImage imageNamed: @"uinavbar.png"];
    [imageView setImage:img];
    [imageView setAlpha:0.5];

    [[self tabBar] addSubview:imageView];
    [imageView release];
    
}
@end