for in 循环只保存 Parse 中的最后一个元素。迅速

Question

我正在对一个 PFUser 数组执行 for in 循环，然后在该 for in 循环中，我希望能够为每个已循环通过的用户设置关键字段。由于某种原因，它只保存了 for in 循环的最后一个元素。有人可以解释我做错了什么吗？代码：

var user2ObjId = ["N7xqk8oFJx", "Q5lPX2DUmP", "mfkO8iypTB"]

let userQuery = PFUser.query()
        userQuery.whereKey("objectId", containedIn: user2ObjId)
        let foundUsers = userQuery.findObjects()
        if foundUsers.count > 0 {
            let addRoomObject = PFObject(className: "Room")
            for user in foundUsers {

                addRoomObject["user1"] = PFUser.currentUser()
                addRoomObject["user2"] = user

                addRoomObject.addObject(2, forKey: "questionNumbers")
                addRoomObject["matchCount"] = 1

            }
            addRoomObject.saveInBackgroundWithBlock({ (success: Bool, error: NSError!) -> Void in
                if success == true {
                   // println("Added new users to room")
                }
            })
        }

在user2ObjId 数组中唯一保存的是mfkO8iypTB。这是为什么呢？

Answer 1

如果您查看 for-in 循环，您将属性设置到同一个实例中，但您在退出循环时会保存，这发生在处理 foundUsers 中的最后一个元素时 - 这解释了原因仅保存最后一个对象。

您可以使用saveAllInBackground

var array = [PFObject]()
for user in foundUsers {
  let addRoomObject = PFObject(className: "Room")

  addRoomObject["user1"] = PFUser.currentUser()
  addRoomObject["user2"] = user

  addRoomObject.addObject(2, forKey: "questionNumbers")
  addRoomObject["matchCount"] = 1

  array.append(addRoomObject)     
}

PFObject.saveAllInBackground(array, block({ (success: Bool, error: NSError!) -> Void in
   if success == true {
       // println("Added new users to room")
   }
})