Block2

1.clang -rewrite-objc 源代码文件名 -> C++源代码

void (^blk)() = ^ {
    printf("Hello world");
};
 
void (^blk2)(int b) = ^(int b) {
    printf("%d", b);
};

C++源代码

 Block本质：指向函数的指针，实质 Objective-C对象
 
 ****************************  main  ***************************
 
 int main(int argc, const char * argv[]) {
 
     void (*blk)() = ((void (*)())&__main_block_impl_0((void *)__main_block_func_0, &__main_block_desc_0_DATA));
     
     void (*blk2)(int b) = ((void (*)(int))&__main_block_impl_1((void *)__main_block_func_1, &__main_block_desc_1_DATA));
 
     return 0;
 }
 
 static void __main_block_func_0(struct __main_block_impl_0 *__cself) {
 
    printf("Hello world");
 }
 
 static void __main_block_func_1(struct __main_block_impl_1 *__cself, int b) {
 
    printf("%d", b);
 }

****************************  blk  ***************************
 
struct __main_block_impl_0 {
    struct __block_impl impl;
    struct __main_block_desc_0* Desc;
 
    __main_block_impl_0(void *fp, struct __main_block_desc_0 *desc, int flags=0) {
        impl.isa = &_NSConcreteStackBlock;
        impl.Flags = flags;
        impl.FuncPtr = fp;
        Desc = desc;
    }
};
 
 static struct __main_block_desc_0 {
     size_t reserved;
     size_t Block_size;
 } __main_block_desc_0_DATA = { 0, sizeof(struct __main_block_impl_0)};
 
 
 ****************************  blk2  ***************************
 
 struct __main_block_impl_1 {
     struct __block_impl impl;
     struct __main_block_desc_1* Desc;
 
     __main_block_impl_1(void *fp, struct __main_block_desc_1 *desc, int flags=0) {
         impl.isa = &_NSConcreteStackBlock;
         impl.Flags = flags;
         impl.FuncPtr = fp;
         Desc = desc;
     }
 };
 
 static struct __main_block_desc_1 {
     size_t reserved;
     size_t Block_size;
 } __main_block_desc_1_DATA = { 0, sizeof(struct __main_block_impl_1)};
 
 
  **************************  __block_impl  *****************************
 
 struct __block_impl {
     //  block为OC对象： _NSConcreteStackBlock、_NSConcreteGlobalBlock、_NSConcreteMallocBlock
     void *isa;
     int Flags;
     int Reserved;
     void *FuncPtr;
 };

自动变量会追加到结构体__main_block_impl_0 中