在iOS开发中经常会在自定义view中push到下一个导航控制器，这时就需要获取当前自定义view所在的导航控制器

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

//获取导航控制器
- (UINavigationController*)navigationController {
    for (UIView* next = [self superview]; next; next = next.superview) {
        UIResponder* nextResponder = [next nextResponder];
        if ([nextResponder isKindOfClass:[UINavigationController class]]) {
            return (UINavigationController*)nextResponder;
        }
    }
    return nil;
}