Block相关

OC代码：

 1 int main(int argc, const char * argv[]) {
 2
 3     void (^blk)(void) = ^{
 4         printf("Block\n");
 5     };
 6
 7     blk();
 8
 9     return 0;
10 }

通过Clang -rewrite-objc命令转成C语言代码：

 1 struct __block_impl {
 2   void *isa;
 3   int Flags;
 4   int Reserved;
 5   void *FuncPtr;
 6 };
 7
 8 struct __main_block_impl_0 {
 9     struct __block_impl impl;
10     struct __main_block_desc_0* Desc;
11     __main_block_impl_0(void *fp, struct __main_block_desc_0 *desc, int flags=0) {
12         impl.isa = &_NSConcreteStackBlock;
13         impl.Flags = flags;
14         impl.FuncPtr = fp;
15         Desc = desc;
16     }
17 };
18
19 static void __main_block_func_0(struct __main_block_impl_0 *__cself) {
20     printf("Block\n");
21 }
22
23 static struct __main_block_desc_0 {
24     size_t reserved;
25     size_t Block_size;
26 } __main_block_desc_0_DATA = { 0, sizeof(struct __main_block_impl_0)};
27
28 int main(int argc, const char * argv[]) {
29
30     void (*blk)(void) = ((void (*)())&__main_block_impl_0((void *)__main_block_func_0, &__main_block_desc_0_DATA));
31
32     ((void (*)(__block_impl *))((__block_impl *)blk)->FuncPtr)((__block_impl *)blk);
33
34     return 0;
35 }

可以看到整个Block结构如下：