一、block的三种形式

堆block：

在堆上的block，
用__block修饰的外部参数，会将block拷贝（copy修饰）到栈上，从栈复制到堆并被block持有

栈block：

在栈上的block
未copy到堆的block，有外部参数
有值域的问题，用__block将block复制到堆解决值域的问题，从而解决值域问题

全局block：

在静态区的block
不使用外部变量的block，或值用static修饰的，是全局block

二、block的copy

堆block：引用计算+1
栈block：会copy到堆block
全局block：啥也不做

图片描述

总结

static NSInteger num1 = 1;
NSInteger num2 = 1;

//static NSMutableArray *marray1 = [NSMutableArray arrayWithArray:@[@1]];
//NSMutableArray static *marray2 = [NSMutableArray arrayWithArray:@[@1]];

//static NSArray *array1 = @[@1];
//NSArray static *marray2 = @[@1];

static NSString *string1 = @"1";
NSString static *string2 = @"1";

int test1(){
    NSInteger num3 = 1;
    static NSInteger num4 = 1;
    __block NSInteger num5 = 1;
    
    NSString *string3 = @"1";
    static NSString *string4 = @"1";
    __block NSString *string5 = @"1";

    NSMutableArray *marray3 = [NSMutableArray arrayWithArray:@[@1]];
//    static NSMutableArray *marray4 = [NSMutableArray arrayWithArray:@[@1]];
    __block NSMutableArray *marray5 = [NSMutableArray arrayWithArray:@[@1]];
    void(^block)(void) = ^{
        NSLog(@"NSInteger");
        NSLog(@"%zd",num1);///全局静态变量
        NSLog(@"%zd",num2);//全局变量
        NSLog(@"%zd",num3);//局部变量
        NSLog(@"%zd",num4);//静态变量
        NSLog(@"%zd",num5);//__block修饰变量
        
        NSLog(@"NSMutableArray");
//        NSLog(@"%@",marray1);
//        NSLog(@"%@",marray2);
        NSLog(@"%@",marray3);
//        NSLog(@"%@",marray4);
        NSLog(@"%@",marray5);
        
        NSLog(@"NSString");
        NSLog(@"%@",string1);
        NSLog(@"%@",string2);
        NSLog(@"%@",string3);
        NSLog(@"%@",string4);
        NSLog(@"%@",string5);
    };
    NSLog(@"---------------------初始化---------------------------");
    block();
    
    num1 = 2;
    num2 = 2;
    num3 = 2;
    num4 = 2;
    num5 = 2;
    string1 = @"2";
    string2 = @"2";
    string3 = @"2";
    string4 = @"2";
    string5 = @"2";
    
    [marray3 addObject:@2];
    [marray5 addObject:@2];
    NSLog(@"---------------------赋值---------------------------");
    block();
    
    string1 = nil;
    string2 = nil;
    string3 = nil;
    string4 = nil;
    string5 = nil;
    
    marray3 = nil;
    marray5 = nil;
    NSLog(@"---------------------赋空---------------------------");
    block();
    
    return 0;
}

2021-01-11 17:44:20.312008+0800 SEEProxy[92404:4949653] ---------------------初始化---------------------------
2021-01-11 17:44:20.312503+0800 SEEProxy[92404:4949653] NSInteger
2021-01-11 17:44:20.312571+0800 SEEProxy[92404:4949653] 1
2021-01-11 17:44:20.312647+0800 SEEProxy[92404:4949653] 1
2021-01-11 17:44:20.312712+0800 SEEProxy[92404:4949653] 1
2021-01-11 17:44:20.312774+0800 SEEProxy[92404:4949653] 1
2021-01-11 17:44:20.312837+0800 SEEProxy[92404:4949653] 1
2021-01-11 17:44:20.312894+0800 SEEProxy[92404:4949653] NSMutableArray
2021-01-11 17:44:20.313099+0800 SEEProxy[92404:4949653] (
    1
)
2021-01-11 17:44:20.313227+0800 SEEProxy[92404:4949653] (
    1
)
2021-01-11 17:44:20.313294+0800 SEEProxy[92404:4949653] NSString
2021-01-11 17:44:20.313454+0800 SEEProxy[92404:4949653] 1
2021-01-11 17:44:20.313617+0800 SEEProxy[92404:4949653] 1
2021-01-11 17:44:20.313804+0800 SEEProxy[92404:4949653] 1
2021-01-11 17:44:20.314039+0800 SEEProxy[92404:4949653] 1
2021-01-11 17:44:20.314218+0800 SEEProxy[92404:4949653] 1
2021-01-11 17:44:20.314432+0800 SEEProxy[92404:4949653] ---------------------赋值---------------------------
2021-01-11 17:44:20.314586+0800 SEEProxy[92404:4949653] NSInteger
2021-01-11 17:44:20.314768+0800 SEEProxy[92404:4949653] 2
2021-01-11 17:44:20.319000+0800 SEEProxy[92404:4949653] 2
2021-01-11 17:44:20.319072+0800 SEEProxy[92404:4949653] 1
2021-01-11 17:44:20.319124+0800 SEEProxy[92404:4949653] 2
2021-01-11 17:44:20.319171+0800 SEEProxy[92404:4949653] 2
2021-01-11 17:44:20.319219+0800 SEEProxy[92404:4949653] NSMutableArray
2021-01-11 17:44:20.319324+0800 SEEProxy[92404:4949653] (
    1,
    2
)
2021-01-11 17:44:20.319385+0800 SEEProxy[92404:4949653] (
    1,
    2
)
2021-01-11 17:44:20.319520+0800 SEEProxy[92404:4949653] NSString
2021-01-11 17:44:20.319754+0800 SEEProxy[92404:4949653] 2
2021-01-11 17:44:20.319991+0800 SEEProxy[92404:4949653] 2
2021-01-11 17:44:20.320205+0800 SEEProxy[92404:4949653] 1
2021-01-11 17:44:20.320428+0800 SEEProxy[92404:4949653] 2
2021-01-11 17:44:20.320654+0800 SEEProxy[92404:4949653] 2
2021-01-11 17:44:20.320873+0800 SEEProxy[92404:4949653] ---------------------赋空---------------------------
2021-01-11 17:44:20.321086+0800 SEEProxy[92404:4949653] NSInteger
2021-01-11 17:44:20.321251+0800 SEEProxy[92404:4949653] 2
2021-01-11 17:44:20.321405+0800 SEEProxy[92404:4949653] 2
2021-01-11 17:44:20.321584+0800 SEEProxy[92404:4949653] 1
2021-01-11 17:44:20.321769+0800 SEEProxy[92404:4949653] 2
2021-01-11 17:44:20.321949+0800 SEEProxy[92404:4949653] 2
2021-01-11 17:44:20.322128+0800 SEEProxy[92404:4949653] NSMutableArray
2021-01-11 17:44:20.322410+0800 SEEProxy[92404:4949653] (
    1,
    2
)
2021-01-11 17:44:20.322596+0800 SEEProxy[92404:4949653] (null)
2021-01-11 17:44:20.322786+0800 SEEProxy[92404:4949653] NSString
2021-01-11 17:44:20.323016+0800 SEEProxy[92404:4949653] (null)
2021-01-11 17:44:20.323245+0800 SEEProxy[92404:4949653] (null)
2021-01-11 17:44:20.323433+0800 SEEProxy[92404:4949653] 1
2021-01-11 17:44:20.323617+0800 SEEProxy[92404:4949653] (null)
2021-01-11 17:44:20.323812+0800 SEEProxy[92404:4949653] (null)
2021-01-11 17:44:20.362871+0800 SEEProxy[92404:4949653] libMobileGestalt MobileGestalt.c:890: MGIsDeviceOneOfType is not supported on this platform.
2021-01-11 17:44:20.457284+0800 SEEProxy[92404:4949653] 我是美人鱼
2021-01-11 17:44:20.457405+0800 SEEProxy[92404:4949653] 我在游泳

以上可看出，除了栈block，其他block都会随着值变化而变化