在Cocoa中，如何定义id类型？ [英] In Cocoa, how is the id type defined?

问题描述

这个问题出于纯粹的好奇心。 Cocoa如何定义id类型？它只是一个void *的typedef？

This question is out of pure curiosity. How does Cocoa define the id type? Is it just a typedef for a void *? Also, if you know which header file it is defined in, I would be interested in taking a look.

推荐答案

如果你知道它定义了哪个头文件，我会感兴趣的。命令键并双击任何突出显示的术语以跳转到其定义。

Hold down the command key and double click on any highlighted term to jump to its definition.

typedef struct objc_class *Class;
typedef struct objc_object {
    Class isa;
} *id;


typedef struct objc_selector    *SEL;    
typedef id          (*IMP)(id, SEL, ...); 

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