block 捕获自动变量的瞬间值；
注释在代码中；请参考傻瓜学编程之block_3
import "People.h"
@interface People()
{
int yourNameis; }
@end @implementation People
-(instancetype)init{
if ( [super init]) {
[self myBlcokTest];
}
return self; } - (void)myBlcokTest{
int ddkknn = 555555;
char bbb = '3';
const char *fmt = &bbb;
void (^blk)()=^{
printf("%d",ddkknn);
printf("%s",fmt); };
blk(); }
// 变量直接添加 属性生成_xxxx;
struct People_IMPL {
struct NSObject_IMPL NSObject_IVARS;
int yourNameis;
NSString *_thisIsPro;
}; /**
1、结构体内部生成的成员变量与声明的成员变量的类型相同；
2、block语法中没有使用的自动变量不会被追加，只有在block语法中使用的自动变量才会被追加；
3、根据构造函数传递过来的参数对追加的成员变量进行初始化；
*/
struct __People__myBlcokTest_block_impl_0 {
struct __block_impl impl;
struct __People__myBlcokTest_block_desc_0* Desc;
int ddkknn;
const char *fmt;
__People__myBlcokTest_block_impl_0(void *fp, struct __People__myBlcokTest_block_desc_0 *desc, int _ddkknn, const char *_fmt, int flags=0) : ddkknn(_ddkknn), fmt(_fmt) {
impl.isa = &_NSConcreteStackBlock;
impl.Flags = flags;
impl.FuncPtr = fp;
Desc = desc;
} // 相当于：
__People__myBlcokTest_block_impl_0(void *fp, struct __People__myBlcokTest_block_desc_0 *desc, int _ddkknn, const char *_fmt, int flags=0) : ddkknn(_ddkknn), fmt(_fmt) {
impl.isa = &_NSConcreteStackBlock;
impl.Flags = flags;
impl.FuncPtr = fp;
Desc = desc;
ddkknn = 5555;
fmt = '3';
}
}; //此时使用的是保存在__People__myBlcokTest_block_impl_0结构体实例的成员变量中那些自动变量的值 即（int ddkknn;
//const char *fmt;） 也就是截获自动变量 就是在执行block时，block所使用的自动变量保存在block 的结构体实例中；
static void __People__myBlcokTest_block_func_0(struct __People__myBlcokTest_block_impl_0 *__cself) {
int ddkknn = __cself->ddkknn; // bound by copy
const char *fmt = __cself->fmt; // bound by copy printf("%d",ddkknn);
printf("%s",fmt); } static struct __People__myBlcokTest_block_desc_0 {
size_t reserved;
size_t Block_size;
} __People__myBlcokTest_block_desc_0_DATA = { 0, sizeof(struct __People__myBlcokTest_block_impl_0)}; static void _I_People_myBlcokTest(People * self, SEL _cmd) {
int ddkknn = 555555;
char bbb = '3';
const char *fmt = &bbb;
void (*blk)()=((void (*)())&__People__myBlcokTest_block_impl_0((void *)__People__myBlcokTest_block_func_0, &__People__myBlcokTest_block_desc_0_DATA, ddkknn, fmt));
((void (*)(__block_impl *))((__block_impl *)blk)->FuncPtr)((__block_impl *)blk); }