SEL和@selector如何工作? [英] How do SEL and @selector work?

问题描述

typedef struct objc_selector  *SEL;

在上面的代码中，objective-c中的SEL类型是指向struct objc_selector的指针.因此，如果我将SEL变量设为:

In the code above, SEL type in objective-c is a pointer to struct objc_selector. So, if I make a SEL variable like:

SEL aSel = @selector(instanceMethod) //Like this

会发生什么? @selector对实例方法instanceMethod做了什么?

What happens? What did @selector do to the instance method, instanceMethod?

推荐答案

@selector指令仅采用方法名称并返回该方法的适当标识符.此标识符用于确定最终执行选择器时要调用的方法:

The @selector directive simply takes a method name and returns an appropriate identifier for that method. This identifier is used to determine which method to invoke when the selector does eventually get performed:

SEL aSel = @selector(instanceMethod);

// Calls -instanceMethod on someObject
[someObject performSelector:aSel];

您可以在 Apple的文档中找到详细信息.

You can find details in Apple's documentation.

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