I have a simple piece of code that places a background image on the tabBar.
UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@
//---- For providing background image to tabbar
UITabBar *tabBar = [tabBarController tabBar];
if ([tabBar respondsToSelector:@selector(setBackgroundImage:)])
{
// ios 5 code here
[tabBar setBackgroundImage:[UIImage imageNamed:@"PB_MD_footer_navBg_v2.png"]];
}
else
{
// ios 4 code here
CGRect frame = CGRectMake(0, 0, 480, 49);
UIView *tabbg_view = [[UIView alloc] initWithFrame:frame];
UIImage *tabbag_image = [UIImage imageNamed:@"PB_MD_footer_navBg_v2.png"];
UIColor *tabbg_color = [[UIColor alloc] initWithPatternImage:tabbag_image];
tabbg_view.backgroundColor = tabbg_color;
[tabBar insertSubview:tabbg_view atIndex:0];
}