1. //三个结构体
    2. //block的结构体定义
    3. struct __main_block_impl_0 {
    4.     struct _block_impl impl;//Block isa ，函数地址等定义
    5.     struct __main_block_desc_0 *Desc;//Block size等信息定义
    6. };
    8. struct _block_impl {
    9.     void *isa;//所属的类
    10.     int Flags;
    11.     int Reserved;
    12.     void *FuncPtr;//函数地址
    13. };
    15. struct __main_block_desc_0 {
    16.     unsigned long reserved;
    17.     unsigned long Block_size;
    18. } 
    20. //两个函数
    21. //Block信息初始化的函数
    22. __main_block_impl_0(void *fp,struct __main_block_desc_0 *desc, int flags=0)
    23. {
    24.     impl.isa = &_NSConcreteStackBlock;
    25.     impl.Flags = flags;
    26.     impl.FuncPtr = fp;
    27.     Desc = desc;
    28. }
    29. //我们的Block里面的函数，_cself就是调用这个函数的调用者的指针
    30. static void __main_block_func_0(struct __main_block_impl_0 *_cself)
    31. {
    32.     printf("Block\n");
    33. }