本文使用的objc源码版本为objc4-756.2。
Class本质上为一个结构体类型:
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| typedef struct objc_class *Class;
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与该结构体相关的主要定义如下:
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| struct objc_object { private: isa_t isa; //以下省略 }
struct objc_class : objc_object { // Class ISA; Class superclass; cache_t cache; // 方法缓存 class_data_bits_t bits; // 类的具体信息 class_rw_t *data() { return bits.data(); } //以下省略 }
struct class_rw_t { // Be warned that Symbolication knows the layout of this structure. uint32_t flags; uint32_t version;
const class_ro_t *ro;
method_array_t methods; //方法列表 property_array_t properties; //属性信息 protocol_array_t protocols; //协议列表 }
struct class_ro_t { uint32_t flags; uint32_t instanceStart; uint32_t instanceSize; //instance对象占用的内存大小 #ifdef __LP64__ uint32_t reserved; #endif
const uint8_t * ivarLayout; const char * name; //类名 method_list_t * baseMethodList; protocol_list_t * baseProtocols; const ivar_list_t * ivars; //成员变量列表
const uint8_t * weakIvarLayout; property_list_t *baseProperties; }
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