Block的测试

Posted 2022-04-25 yuxiaoyiyou

//输出10
int x = 10;
    void(^function)(void)  = ^(void) 
        printf("-----> %d",x);
    ;
    x = 12;
    function();

//输出12
int __block  x = 10;
    void(^function)(void)  = ^(void) 
        printf("-----> %d",x);
    ;
    x = 12;
    function();

 上面两个换成NSString一样是这种情况，带__block才会输出后面配置的新值。

//输出ab
int __block x = 10;
    NSMutableString *y = [NSMutableString stringWithString:@"a"];
    void(^function)(void)  = ^(void) 
        printf("-----> %d\n",x);
        printf("++++>%s",[y UTF8String]);
    ;
    x = 12;
    [y appendString:@"b"];
    function();

可变对象没有变化