orderByDescending（＆＃34; createdAt＆＃34;）解析查询

Question

我正在尝试使用orderByDescending("createdAt")从parse.com发出检索数据的订单。我的代码如下：

 var postQuery:PFQuery = PFQuery(className: "Posts")              
     postQuery.whereKey("postedBy", equalTo: followedUser)           
     postQuery.orderByDescending("createdAt")  
     postQuery.findObjectsInBackgroundWithBlock ({ (objects, error) -> Void in

         if let objects = objects {

                 for object in objects {
                            println(object.createdAt)
                     if let post = object as? PFObject {

                          self.data.addObject(object)

但它不起作用..数据以随机顺序出现。 println(object.createdAt给出：

Optional(2015-08-25 22:25:36 +0000)
Optional(2015-08-24 13:39:25 +0000)
Optional(2015-08-25 22:28:28 +0000)
Optional(2015-08-24 13:40:48 +0000)

我的完整代码是：

  func loadData() {

    var followersQuery : PFQuery = PFQuery(className: "Followers")

    followersQuery.whereKey("follower", equalTo: PFUser.currentUser()!.objectId!)
    followersQuery.findObjectsInBackgroundWithBlock { (objects, error) -> Void in

        if let followers = objects {

            for users in followers {

                var followedUserId = users["user"] as! String

                    println(followedUserId)

                var postQuery:PFQuery = PFQuery(className: "Posts")
                    postQuery.orderByDescending("createdAt")
                    postQuery.whereKey("postedBy", equalTo: followedUserId)
                postQuery.findObjectsInBackgroundWithBlock({ (objects, error) -> Void in

                    if let objects = objects {

                        for object in objects {

                            println(object.createdAt)

                            self.data.addObject(object)

                           // println(self.data)

                        }

                    }
                })

            }

        }


    }


}

感谢您的时间。