从 Parse.com 中的指针检索 pfobject 数据的问题

Question

我在从解析查询中获得的对象中的指针获取数据时遇到问题。我在查询中使用了包含键，但在从返回的对象数组中获取包含键信息时遇到问题。我创建了一个 for 循环来迭代结果，但不确定如何将它们存储回数组中。下面是我的代码：

- (void) loadUsersPFUserIsFollowing
    {


        //Retrieving PFUser Curren Users followers and storing in Array
        PFQuery *queryFollowingCount = [PFQuery queryWithClassName:@"Activity"];
        [queryFollowingCount whereKey:@"type" equalTo:@"follow"];
        [queryFollowingCount whereKey:@"fromUser" equalTo:[PFUser currentUser]];

        //Access the the user following informatioin
        [queryFollowingCount includeKey:@"toUser"];

        //[queryFollowingCount setCachePolicy:kPFCachePolicyCacheThenNetwork];

        [queryFollowingCount findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
            [HUD hide:YES];
            if (!error) {

               searchResultsArray = [[NSArray alloc] initWithArray:objects];            

               NSLog(@"%@", objects);

                for (PFObject * postObject in objects) {

                   PFObject *postAuthor = [postObject objectForKey:@"toUser"][@"username"];



                    NSLog(@"retrieved related Post Author: %@", postAuthor);
                }

                  [self.tableView reloadData];

            } else {
                NSLog(@"Something went wrong");
                NSLog(@"%@", error);
            }
        }];

    }

Answer 1

for (PFObject * postObject in objects) {
     PFObject *postAuthor = [postObject objectForKey:@"toUser"][@"username"];

     NSLog(@"retrieved related Post Author: %@", postAuthor);
}

默认情况下，在获取对象时，不会获取相关的 PFObject。这些对象的值在被获取之前无法检索，如下所示：

for (PFObject * postObject in objects) {

     //Im assuming in your code, postObject is either nil or it's there but it's values are nil except its objectId. We need to fetch this object. 
     [postObject fetchIfNeededInBackgroundWithBlock:^(PFObject *object, NSError *error){

          PFObject *postAuthor = [object objectForKey:@"toUser"][@"username"];

          NSLog(@"retrieved related Post Author: %@", postAuthor);

         [self.tableView reloadData];

      }];
}