block

    __block int i = 0;
    int (^count)(void) = ^ {
        i += 1;
        return i;
    };
    NSLog(@"%d", count());    // 1
    NSLog(@"%d", count());    // 2
    NSLog(@"%d", count());    // 3
    
    
    int q = 42;
    __block int ssy = 1;
    void (^block)() = ^() {
        printf("1111111111111111  %d\n", q);  //42
        printf("2222222222222222  %d\n", ssy);//1 2
    };

    block();
    //输出 42  1
    ssy = 2;
    q = 1;
    
    block();
    //输出 42  2