Find the tags that are used in a view hierarchy so you don't interfere with existing tags!

gistfile1.txt

- (NSMutableSet *)recurIntoView:(UIView *)v {
    NSMutableSet *s = [NSMutableSet set];
    for (UIView *sv in v.subviews) {
        [s addObject:[NSNumber numberWithInt:sv.tag]];
        [s unionSet:[self recurIntoView:sv]];
    }
    return s;
}