Objective C switch 语句和命名整型常量

发布于 2024-10-08 18:10:43 字数 492 浏览 4 评论 0原文

我有一个控制器，它充当两个滚动视图的委托，这两个滚动视图放置在由上述视图控制器管理的视图中。

为了区分两个滚动视图，我尝试使用 switch 语句（而不是与 if 语句进行简单的指针比较）。我已将两个滚动视图标记为 0 和 1，如下所示

NSUInteger const kFirstScrollView = 0;
NSUInteger const kSecondScrollView = 1;

当我尝试在 switch 语句中使用这些常量时，编译器表示 case 语句不是常量。

switch (scrollView.tag) {
    case kFirstScrollView: {
      // do stuff
    }
    case kSecondScrollView: {
      // do stuff
    }
}

我做错了什么？

原文

I have a controller which serves as a delegate to two scrollviews which are placed in view managed by aforementioned view controller.

To distinguish between two scroll views I'm trying to use switch statement (instead of simple pointer comparison with if statement). I have tagged both scroll views as 0 and 1 like this

NSUInteger const kFirstScrollView = 0;
NSUInteger const kSecondScrollView = 1;

When I try to use these constants in a switch statement, the compiler says that case statements are not constants.

switch (scrollView.tag) {
    case kFirstScrollView: {
      // do stuff
    }
    case kSecondScrollView: {
      // do stuff
    }
}

What am I doing wrong?

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

妥活 2024-10-15 18:10:43

这可以通过使用匿名（尽管不一定如此）enum类型来解决：

enum {
    kFirstScrollView = 0,
    kSecondScrollView = 1
};

switch (scrollView.tag) {
    case kFirstScrollView: {
      // do stuff
    }
    case kSecondScrollView: {
      // do stuff
    }
}

这将编译没有错误。

This can be solved through the use of an anonymous (though not necessarily so) enum type:

enum {
    kFirstScrollView = 0,
    kSecondScrollView = 1
};

switch (scrollView.tag) {
    case kFirstScrollView: {
      // do stuff
    }
    case kSecondScrollView: {
      // do stuff
    }
}

This will compile without errors.

回复收藏 0 原文