Changing Tint / Background color of UITabBar

I have an addendum to the final answer. While the essential scheme is correct, the trick of using a partially transparent color can be improved upon. I assume that it's only for letting the default gradient to show through. Oh, also, the height of the TabBar is 49 pixels rather than 48, at least in OS 3.

So, if you have a appropriate 1 x 49 image with a gradient, this is the version of viewDidLoad you should use:

- (void)viewDidLoad {

    [super viewDidLoad]; 

    CGRect frame = CGRectMake(0, 0, 480, 49);
    UIView *v = [[UIView alloc] initWithFrame:frame];
    UIImage *i = [UIImage imageNamed:@"GO-21-TabBarColorx49.png"];
    UIColor *c = [[UIColor alloc] initWithPatternImage:i];
    v.backgroundColor = c;
    [c release];
    [[self tabBar] addSubview:v];
    [v release];

}

I have been able to make it work by subclassing a UITabBarController and using private classes:

@interface UITabBarController (private)
- (UITabBar *)tabBar;
@end

@implementation CustomUITabBarController


- (void)viewDidLoad {
    [super viewDidLoad];

    CGRect frame = CGRectMake(0.0, 0.0, self.view.bounds.size.width, 48);
    UIView *v = [[UIView alloc] initWithFrame:frame];
    [v setBackgroundColor:kMainColor];
    [v setAlpha:0.5];
    [[self tabBar] addSubview:v];
    [v release];

}
@end

iOS 5 has added some new appearance methods for customising the look of most UI elements.

You can target every instance of a UITabBar in your app by using the appearance proxy.

For iOS 5 + 6:

[[UITabBar appearance] setTintColor:[UIColor redColor]];

For iOS 7 and above, please use the following:

[[UITabBar appearance] setBarTintColor:[UIColor redColor]];

Using the appearance proxy will change any tab bar instance throughout the app. For a specific instance, use one of the new properties on that class:

UIColor *tintColor; // iOS 5+6
UIColor *barTintColor; // iOS 7+
UIColor *selectedImageTintColor;
UIImage *backgroundImage;
UIImage *selectionIndicatorImage;

When you just use addSubview your buttons will lose clickability, so instead of

[[self tabBar] addSubview:v];

use:

[[self tabBar] insertSubview:v atIndex:0];