__blockこわい

        __block NSNumber *val = [NSNumber numberWithInt:0];
        void (^blk)(void) = ^{
            __block NSNumber *val1 = val;
            void (^blk2)(void) = ^{
                val1 = [NSNumber numberWithInt:1];
            };
            NSLog(@"val:%@ val1:%@", val, val1);
            val = [NSNumber numberWithInt:2];
            NSLog(@"val:%@ val1:%@", val, val1);
            val1 = [NSNumber numberWithInt:3];
            NSLog(@"val:%@ val1:%@", val, val1);
            blk2();
            NSLog(@"val:%@ val1:%@", val, val1);
        };
        blk();
        NSLog(@"val:%@", val);