说明：

<1>阅读本文，最好阅读之前的block文章加以理解；

<2>本文内容：三种block类型的copy情况（MRC）、是否深拷贝、错误copy；

 

一、MRC模式下，三种block类型的copy情况

//代码

void test1()
{
    int age = 10;
    
    void(^block1)(void) = ^{
        NSLog(@"-----");
    };
    
    void(^block2)(void) = ^{
        NSLog(@"-----%d", age);
    };
    
    id block3 = [block2 copy];
    
    NSLog(@"%@ %@ %@", [block1 class], [block2 class], [block3 class]);
    NSLog(@"%@ %@ %@", [[block1 copy] class], [[block2 copy] class], [[block3 copy] class]);
}

//打印

2019-01-11 14:14:06.902974+0800 MJ_TEST[2183:154918] __NSGlobalBlock__ __NSStackBlock__ __NSMallocBlock__
2019-01-11 14:14:06.903260+0800 MJ_TEST[2183:154918] __NSGlobalBlock__ __NSMallocBlock__ __NSMallocBlock__
Program ended with exit code: 0

分析：

<1>只有stack类型block实例对象copy后的类型变为malloc，这个前面文章已经讨论过，没有问题；

<2>global类型实例对象存储在数据区，copy操作其实什么也没做；malloc在堆区，copy之后肯定还是在堆区，但不会开辟新的内存，只是引用计数加1——此处分析，可以通过clang和地址、引用计数打印来查看，此处不再赘述；

结论： 

补充：上述copy的操作是针对block实例对象，那么类对象是存在哪个区呢？往下看

//代码

int a = 20;

void test2()
{
    int b = 10;
    
    void(^block1)(void) = ^{
        NSLog(@"-----");
    };
    
    void(^block2)(void) = ^{
        NSLog(@"-----%d", b);
    };
    
    id block3 = [block2 copy];
    
    id block1Cls = object_getClass(block1);
    id block2Cls = object_getClass(block2);
    id block3Cls = object_getClass(block3);
    
    NSLog(@"a--global--%p", &a);
    NSLog(@"b--auto place--%p", &b);
    NSLog(@"alloc----%p", [[NSObject alloc] init]);
    NSLog(@"Person----%p", [Person class]);
    
    NSLog(@"------block---instance---");
    NSLog(@"block1----%@ %p", [block1 class], block1);
    NSLog(@"block2----%@ %p", [block2 class], block2);
    NSLog(@"block3----%@ %p", [block3 class], block3);
    
    NSLog(@"------block---Class---");
    NSLog(@"block1Cls----%@ %p", block1Cls, block1Cls);
    NSLog(@"block2Cls----%@ %p", block2Cls, block2Cls);
    NSLog(@"block3Cls----%@ %p", block3Cls, block3Cls);
}

//打印

2019-01-11 14:58:29.922125+0800 MJ_TEST[2443:177646] a--global--0x100002520
2019-01-11 14:58:29.922498+0800 MJ_TEST[2443:177646] b--auto place--0x7ffeefbff59c
2019-01-11 14:58:29.922525+0800 MJ_TEST[2443:177646] alloc----0x100526420
2019-01-11 14:58:29.922561+0800 MJ_TEST[2443:177646] Person----0x1000024f8
2019-01-11 14:58:29.922585+0800 MJ_TEST[2443:177646] ------block---instance---
2019-01-11 14:58:29.922639+0800 MJ_TEST[2443:177646] block1----__NSGlobalBlock__ 0x1000020c0
2019-01-11 14:58:29.922666+0800 MJ_TEST[2443:177646] block2----__NSStackBlock__ 0x7ffeefbff560
2019-01-11 14:58:29.922699+0800 MJ_TEST[2443:177646] block3----__NSMallocBlock__ 0x102812000
2019-01-11 14:58:29.922717+0800 MJ_TEST[2443:177646] ------block---Class---
2019-01-11 14:58:29.922736+0800 MJ_TEST[2443:177646] block1Cls----__NSGlobalBlock__ 0x7fffb33c3460
2019-01-11 14:58:29.922756+0800 MJ_TEST[2443:177646] block2Cls----__NSStackBlock__ 0x7fffb33c3060
2019-01-11 14:58:29.922777+0800 MJ_TEST[2443:177646] block3Cls----__NSMallocBlock__ 0x7fffb33c3160
Program ended with exit code: 0

分析：

<1>Person类对象：打印出的类对象Person的地址跟全局变量a和global