响应链的特殊用法

Paste_Image.png

//获取某个view所在的控制器
- (UIViewController *)viewController {
  UIViewController *viewController = nil;
  UIResponder *next = self.nextResponder;
  while (next) {
    if ([next isKindOfClass:[UIViewController class]]) {
      viewController = (UIViewController *)next;
      break;
    }
    next = next.nextResponder;
  }
  return viewController;
}