NSComparisonResult和NSComparator - 它们是什么？ [英] NSComparisonResult and NSComparator - what are they?

问题描述

什么是 NSComparisonResult 和 NSComparator ？

我见过其中一个类型定义，类似于：

I've seen one of the type definitions, something like that:

typedef NSComparisonResult (^NSComparator)(id obj1, id obj2);

与函数指针有什么不同吗？

Is it any different from a function pointer?

另外，我甚至无法猜出 ^ 符号的含义。

Also, I can't even guess what the ^ symbol means.

推荐答案

^ 表示块类型，在概念上类似于函数指针。

^ signifies a block type, similar in concept to a function pointer.

typedef NSComparisonResult (^NSComparator)(id obj1, id obj2);
//          ^                      ^                ^
//   return type of block      type name       arguments

这意味着类型 NSComparator 是一个块，它接收两个类型为 id 调用 obj1 和 obj2 ，并返回 NSComparisonResult 。

This means that the type NSComparator is a block that takes in two objects of type id called obj1 and obj2, and returns an NSComparisonResult.

具体 NSComparator 在基础数据类型参考。

要了解有关C块的更多信息，请查看此ADC文章阻止编程主题。

And to learn more about C blocks, check out this ADC article Blocks Programming Topics.

示例：

NSComparator compareStuff = ^(id obj1, id obj2) {
   return NSOrderedSame;
};

NSComparisonResult compResult = compareStuff(someObject, someOtherObject);

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