常见源码解析

block源码

struct __block_impl {
  void *isa;
  int Flags;
  int Reserved;
  void *FuncPtr;
};

static struct __ViewController__viewDidLoad_block_desc_0 {
  size_t reserved;
  size_t Block_size;
} __ViewController__viewDidLoad_block_desc_0_DATA = { 0, sizeof(struct __ViewController__viewDidLoad_block_impl_0)};

struct __ViewController__viewDidLoad_block_impl_0 {
  struct __block_impl impl;
  struct __ViewController__viewDidLoad_block_desc_0* Desc;
  int age;
  __ViewController__viewDidLoad_block_impl_0(void *fp, struct __ViewController__viewDidLoad_block_desc_0 *desc, int _age, int flags=0) : age(_age) {
    impl.isa = &_NSConcreteStackBlock;
    impl.Flags = flags;
    impl.FuncPtr = fp;
    Desc = desc;
  }
};

static void __ViewController__viewDidLoad_block_func_0(struct __ViewController__viewDidLoad_block_impl_0 *__cself) {
  int age = __cself->age; // bound by copy

        NSLog((NSString *)&__NSConstantStringImpl__var_folders_zs_r4g726_d3rd7y0hvw0_7ckym0000gn_T_ViewController_3bd104_mi_0,age);
    }


static void _I_ViewController_viewDidLoad(ViewController * self, SEL _cmd) {
    ((void (*)(__rw_objc_super *, SEL))(void *)objc_msgSendSuper)((__rw_objc_super){(id)self, (id)class_getSuperclass(objc_getClass("ViewController"))}, sel_registerName("viewDidLoad"));
    int age = 10;
    void (*blockName)(void) = ((void (*)())&__ViewController__viewDidLoad_block_impl_0((void *)__ViewController__viewDidLoad_block_func_0, &__ViewController__viewDidLoad_block_desc_0_DATA, age));
    ((void (*)(__block_impl *))((__block_impl *)blockName)->FuncPtr)((__block_impl *)blockName);

}

class源码 typedef struct objc_class *Class;

struct objc_class {    
    Class isa; 
    Class superclass;
    cache_t cache;
    class_data_bits_t bits;
}

struct class_rw_t {
    const class_ro_t * ro;
    method_array_t * methods;
    property_array_t * properties;
    protocol_array_t * protocols;
    ...
}

struct class_ro_t {
    const char * name;
    method_list_t * baseMethodList;
    protocol_list_t * baseProtocols;
    properte_list_t * baseProperties;
    ivar_list_t * ivars;
}

typedef struct objc_object *id;

struct objc_object {
private:m
    isa_t isa; // arm64之前是 Class *isa。arm64之后是isa_t isa。

public:
    // ISA() assumes this is NOT a tagged pointer object
    Class ISA();
};

isa_t源码

union isa_t {
    isa_t() { }
    isa_t(uintptr_t value) : bits(value) { }

    Class cls;
    uintptr_t bits;
#if defined(ISA_BITFIELD)
    struct {
        ISA_BITFIELD;  // defined in isa.h
    };
#endif
};

method_t源码

struct method_t {
    SEL name; // 方法名
    const char *types; // 编码（返回值类型、参数类型）
    MethodListIMP imp; // 指向函数的指针

    struct SortBySELAddress :
        public std::binary_function
    {
        bool operator() (const method_t& lhs,
                         const method_t& rhs)
        { return lhs.name < rhs.name; }
    };
};

catch_t源码

struct catch_t {
    struct bucket_t *_buckets; // 散列表
    mask_t _mask; // 散列表的长度-1
    mask_t _occupied; // 已经缓存的方法数量
    
};

bucket_t源码

struct bucket_t {
    catch_key_t key; // SEL 作为key
    IMP _imp; // 函数的内存地址
}

category_t

struct category_t {
    const char *name;
    classref_t cls;
    struct method_list_t * instanceMethods;
    strcut method_list_t * classMethods;
    struct protocol_list_t *ptotocols;
    struct property_list_t *instanceProperties;
    struct propertity_list_t *_classProperties;
    method_list_t *methodsForMeta(bool isMeta) {
        if (isMeta) return classMethods;
        else return instanceMethods;
    }
    property_list_t *propertiesForMeta(bool isMeta, struct header_info *hi);
}