IntPointer Scope in OC with Block

Async.m

void (^block2)(NSUInteger *) = ^(NSUInteger *count){
    (*count)--;
    NSLog(@"\nblock2:\n*count: %d\ncount: %x", *count, count);
};

void (^block1)(NSUInteger *) = ^(NSUInteger *count){
    NSLog(@"\nblock1:\n*count: %d\ncount: %x", *count, count);
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        sleep(3);
        block2(count);
    });
};

NSUInteger count = 4;

block1(&count);

WithoutAsync.m

void (^block2)(NSUInteger *) = ^(NSUInteger *count){
    (*count)--;
    NSLog(@"\nblock2:\n*count: %d\ncount: %x", *count, count);
};

void (^block1)(NSUInteger *) = ^(NSUInteger *count){
    NSLog(@"\nblock1:\n*count: %d\ncount: %x", *count, count);
    sleep(3);
    block2(count);
};

NSUInteger count = 4;

block1(&count);

Async.m's result is not expected