On iOS7.0.3 - 7.0.6, my searchBar colour is Gold/yellow colour like this:

But
None of the above answers worked for me on iOS 7/8. Here's some setup code that did the trick:
searchBar = [[UISearchBar alloc] initWithFrame:CGRectMake(0, 0, CGRectGetWidth(self.view.frame), 44)];
searchBar.scopeButtonTitles = @[@"Scope1", @"Scope2"];
searchBar.selectedScopeButtonIndex = 0;
searchBar.backgroundColor = [UIColor clearColor];
searchBar.barTintColor = [UIColor clearColor];
searchBar.translucent = YES; // SUPER IMPORTANT, REMOVING THIS MESSED UP THE SCOPE BAR
// ONLY USE IMAGES, NOT BACKGROUND COLORS
UIImage *searchBarBackgroundImage = [[UIImage imageNamed:@"SearchBarBackgroundImage"];
UIImage *scopeBarBackgroundImage = [[UIImage imageNamed:@"ScopeBarBackgroundImage"];
[searchBar setBackgroundImage:searchBarBackgroundImage
               forBarPosition:UIBarPositionAny
                   barMetrics:UIBarMetricsDefault];
searchBar.scopeBarBackgroundImage = scopeBarBackgroundImage;
searchBar.tintColor = [UIColor whiteColor];