This is a category on UIApplication that (as of iOS 7) lets you set the status bar foreground color (which is used as the color for things like the system time, signal strength indicators, and "alarm set" icon — everything in the status bar, except the battery indicator). I'm pretty sure it would pass App Store validation, but hopefully a review…

UIApplication+StatusBarForegroundColor.m

@implementation UIApplication (StatusBarForegroundColor)

- (void)setStatusBarForegroundColor:(UIColor *)foregroundColor {
    SEL statusBarSelector = NSSelectorFromString(@"statusBar");
    if ([self respondsToSelector:statusBarSelector]) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Warc-performSelector-leaks"
        id statusBar = [[UIApplication sharedApplication] performSelector:statusBarSelector
                                                               withObject:nil];
        /*
         Q: "What if the status bar is green or whatever? Don't you need
         to check for a double-height status bar?"
         
         A: Thanks for your question. Nope. iOS takes care of it. Set
         the status bar's foreground color in your app and that's the
         color it will be in your app. If the system changes the status
         bar foreground color (e.g. making it white when making the status
         bar double-height with a green background), it will be restored
         to your color when iOS gets rid of the double-height status bar.
         */
        SEL colorSelector = NSSelectorFromString(@"setForegroundColor:");
        if ([statusBar respondsToSelector:colorSelector]) {
            [statusBar performSelector:colorSelector withObject:foregroundColor];
        }
#pragma clang diagnostic pop
    }
}

@end