What I tried before using a solid image.

How Not To Style UISearchBar

- (void)searchDisplayControllerWillBeginSearch:(UISearchDisplayController *)controller
{
    [self colorAllTheViews:self.searchDisplayController.searchBar.superview];
}

- (void)searchDisplayControllerDidBeginSearch:(UISearchDisplayController *)controller
{
    [self fungeBackdrop];
}
- (void)searchDisplayControllerWillEndSearch:(UISearchDisplayController *)controller
{
    NSLog(@"Search will end.");
}

- (void)fungeBackdrop
{
    UIView *backdrop = [self backdropViewInSearchBar:self.searchDisplayController.searchBar.superview];
    
    backdrop.opaque = YES;
    backdrop.backgroundColor = [BRKThemeManager sharedManager].maroonColor;
 

}

/**
 *
 */

- (void)colorAllTheViews:(UIView *)view
{
    for (UIView *subview in view.subviews)
    {
//        
        if (subview.alpha == 0.85)
        {
            subview.alpha = 1.0;
            subview.backgroundColor = [BRKThemeManager sharedManager].maroonColor;
            
            [self colorAllTheViews:subview];
        }
    }
}

/**
 *  Attempt to extract private view. Whelp!
 */

- (UIView *)backdropViewInSearchBar:(UIView *)view
{
    UIView *backdrop = nil;
    
    for (UIView *subview in view.subviews)
    {
        backdrop = [self backdropViewInSearchBar:subview];
        
        if(!backdrop)
        {
            NSString *className = [NSStringFromClass([subview class]) lowercaseString];
            BOOL isBackdrop = [className rangeOfString:@"back"].location != NSNotFound;
            
            if (isBackdrop) {
                backdrop = subview;
                break;
            }
        }
    }
    
    return backdrop;
}