Ios Firebase观察者最初设置值，但在进行更改时不更新

我尝试设置一个函数来侦听数据库某个部分中的更改：

private func observeParticipants() {

    let databaseRef = FIRDatabase.database().reference()

    let groupRef = databaseRef.child("groups").child(currentRoomID).child("participants")
    groupRef.observe(.childAdded, with: { snapshot in
        print("observe snapshot.value: \(snapshot.value)")
        if let snapDict = snapshot.value as? [String:AnyObject] {

            for each in snapDict {

                let uid  = each.key
                let avatar = each.value["profilePicture"] as! String
                let gender = each.value["gender"] as! String
                let handle = each.value["handle"] as! String
                let name = each.value["name"] as! String
                let status = each.value["status"] as! String

                // Set those to the dictionaries [UID : value]
                self.avatarDictionary.setValue(avatar, forKey: uid)
                self.nameDictionary.setValue(name, forKey: uid)
                self.genderDictionary.setValue(gender, forKey: uid)
                self.handleDictionary.setValue(handle, forKey: uid)
                self.statusDictionary.setValue(status, forKey: uid)
                print("\n\navatarDictionary:\n \(self.avatarDictionary)")
                print("\nhandleDictionary:\n \(self.handleDictionary)")
                print("\ngenderDictionary:\n \(self.genderDictionary)")
                print("\nnameDictionary:\n \(self.nameDictionary)")
                print("\nstatusDictionary:\n \(self.statusDictionary)")
                self.navBarCollectionView.reloadData()
            }
        }
    })
}

当我运行它时，它会加载正确的值，但是如果我进行了更改，例如向组中添加新用户，它不会反映该更改。数据库更新得很好，但观察者没有看到。我有没有办法重新写这篇文章，以便正确观察？如果有帮助的话，我可以发布我的数据库结构

谢谢

编辑：数据库结构：

编辑：snapshot.value添加第二个用户后：

Snapshot.value: Optional({
    gender = female;
    handle = sav;
    name = Savina;
    profilePicture = "https://graph.facebook.com/1929991317219760/picture?type=large&return_ssl_resources=1";
    status = F8B016;
})

编辑2：

这是用于最初获取所有用户值的代码，每次我离开视图并返回时也是如此。它只是不能正确地充当观察者，即如果我添加一个参与者，它就看不到这一点，并更新必要的值，例如集合视图。我必须离开这里，回来让这一切发生

func getParticipantInfo() {

    let databaseRef = FIRDatabase.database().reference()

    let groupRef = databaseRef.child("groups").child(currentRoomIdGlobal)
    groupRef.observe(.childAdded, with: { snapshot in

        if let snapDict = snapshot.value as? [String : AnyObject] {

            for each in snapDict {

                let uid  = each.key
                let avatar = each.value["profilePicture"] as! String
                let gender = each.value["gender"] as! String
                let handle = each.value["handle"] as! String
                let name = each.value["name"] as! String
                let status = each.value["status"] as! String

                // Set those to the dictionaries [UID : value]
                self.avatarDictionary.setValue(avatar, forKey: uid)
                self.nameDictionary.setValue(name, forKey: uid)
                self.genderDictionary.setValue(gender, forKey: uid)
                self.handleDictionary.setValue(handle, forKey: uid)
                self.statusDictionary.setValue(status, forKey: uid)
                print("\n\navatarDictionary:\n \(self.avatarDictionary)")
                print("\nhandleDictionary:\n \(self.handleDictionary)")
                print("\ngenderDictionary:\n \(self.genderDictionary)")
                print("\nnameDictionary:\n \(self.nameDictionary)")
                print("\nstatusDictionary:\n \(self.statusDictionary)")
                self.navBarCollectionView.reloadData()
            }
        }
    })
}

---

你能发布你的数据库结构吗？给你：如果currentRoomId是你刚才在“groups”下面的childByAutoID，我认为你应该观察“参与者”。试试看！我的意思是让groupRef=databaseRef.child（“groups”）.child（currentRoomID）.child（“参与者”）在

.child（currentRoomID）

之后添加

.child（“参与者”）

会导致崩溃，在循环的第一个值上意外地发现零（

让avatar=each.value[“profilePicture”]as！String

）