视图寻找其所在的ViewController

- (UIViewController*)viewController
{
    for (UIView* next = [self superview]; next; next = next.superview) {
        UIResponder* nextResponder = [next nextResponder];
        if ([nextResponder isKindOfClass:[UIViewController class]]) {
            return (UIViewController*)nextResponder;
        }
    }
    return nil;
}