ios - Swift Firebase 从多个节点读取

Question

我正在尝试解决以下问题:我想使用跨两个节点的匹配信息填充 Collection View 单元格，并且需要在“播放器”节点中多次读取。

这是我的 Firebase 数据库结构

{
    Players:
        LpWgezRkC6EWS0sjXEWxhFl2: {
            userName: 'John Doe'
            teamId: '234'
            teamName: 'Revenge'
            teamLogo: 'star.png'
            etc...
        },
        RfskjEWSkdsjkjdskjsd12fg: {
            userName: 'Jane Doe'
            teamId: '987'
            teamName: 'Frills'
            teamLogo: 'jag.png'
            etc...
        }
    },
    Matches: 
        12345: {
            User1: 'LpWgezRkC6EWS0sjXEWxhFl2'
            User2: 'RfskjEWSkdsjkjdskjsd12fg'             
            date: '11/10/17'
            WeekId: 19
            etc...
        }
    }
}

如您所见，“Matches”节点包含“Players”信息，因此在 Collection View 中我希望显示 player1 与 player2 的信息。

我目前的代码是这样的:

self.ref.queryOrdered(byChild: "WeekId").queryEqual(toValue: 19).observe(.value, with: { snapshot in 

    var items: [Match] = []

    for item in snapshot.children {

        let snapshotValue = (item as! DataSnapshot).value as? NSDictionary

        let pId1 = snapshotValue!["User1"] as! NSString
        let pId2 = snapshotValue!["User2"] as! NSString

        let match = Match(snapshot: item as! DataSnapshot)

        items.append(match)

    }

    self.matches = items

    self.collectionView?.reloadData()
}

我不太确定如何对“玩家”节点进行第二次查找(我需要 2 个)，因为它需要查找两个玩家的信息，所有这些都不会超过 let match = Match(snapshot : item as!DataSnapshot) 函数，否则会失败？

谁能帮帮我!

Answer 1

可以添加

self.ref.queryOrdered(byChild: "WeekId").queryEqual(toValue: 19).observe(.value, with: { snapshot in

        var items: [Match] = []

        for item in snapshot.children {

            let snapshotValue = (item as! DataSnapshot).value as? NSDictionary

            let pId1 = snapshotValue!["User1"] as! NSString
            let pId2 = snapshotValue!["User2"] as! NSString

            fetchUserProfile(withUID: pId1, completion: { (userDict1) in
                // Here you get the userDict 1
                self.fetchUserProfile(withUID: pId2, completion: { (userDict2) in
                    //Here you get the user dict 2
                    let match = Match(snapshot: item as! DataSnapshot)
                    items.append(match)
                })
            })
        }

        self.matches = items

        self.collectionView?.reloadData()
    })

//完成获取用户资料

func fetchUserProfile(withUID uid: String, completion: @escaping (_ profileDict: [String: Any]) -> Void) {
    // New code
    Database.database().reference().child(uid).observe(.value, with: { snapshot in
        // Here you can get the snapshot of user1
        guard let snapDict = snapshot.value as? [String: Any] else {return}
        completion(snapDict)
    })
}

我认为这不是解决此问题的正确方法。我建议您捕获所有用户的 pID 并将其保存在一组 UserProfiles 中。需要时，您可以从该数组中获取用户配置文件。希望对您有所帮助。