使用 swiftyJSON/swift 从 Firebase 解析排行榜数据

Posted 2023-03-10

【中文标题】使用 swiftyJSON/swift 从 Firebase 解析排行榜数据

【英文标题】：Parsing leaderboard data from Firebase, using swiftyJSON/swift

【发布时间】：2016-03-06 02:13:11

【问题描述】：

我正在尝试从 Firebase 中提取排行榜数据。当我查看“快照”数据时，我能够以正确的顺序获取数据。一旦我到达 var json = JSON(snapshot.value) 的行，数据就会失去其顺序。

我正在尝试将数据解析为 swift 对象，以便它们可以在我的 swift 应用程序中作为有序排行榜使用/显示。我可以很容易地找到我的数据出现故障的解决方法，但这让我很困扰。

func getScoresData() 
    let scoresRef = ref.childByAppendingPath("/High Scores")

    scoresRef.queryLimitedToFirst(10).observeSingleEventOfType(.Value, withBlock:  snapshot in
        print(snapshot)
        var json = JSON(snapshot.value)
        print(json)

        let theKeys = json.dictionary!.keys

        for key in theKeys 

            self.timeStampArray.append(key)

            let tempName = json[key]["Name"]
            self.namesArray.append(String(tempName))

            let tempScore = json[key]["Score"]
            self.scoresArray.append(String(tempScore))
        
    )

这是我从打印（快照）中正确排序的输出：

Snap (High Scores) 
    "-KC3MktE1jS5z9-tTEgJ" =     
        ".priority" = "-9";
        Date = "1457140993.669797";
        Name = brendan;
        Score = 9;
        UUID = "BD561F1C-72A8-4A01-A71A-850682E49D61";
    ;
"-KC3MktM-rWmoitem8na" =     
    ".priority" = "-9";
    Date = "1457140993.677347";
    Name = brendan;
    Score = 9;
    UUID = "BD561F1C-72A8-4A01-A71A-850682E49D61";
;
"-KC3MktW0iJfkAKjlCy4" =     
    ".priority" = "-9";
    Date = "1457140993.686348";
    Name = brendan;
    Score = 9;
    UUID = "BD561F1C-72A8-4A01-A71A-850682E49D61";
;
"-KC3MktapH6Mebw2sAUe" =     
    ".priority" = "-10";
    Date = "1457140993.692581";
    Name = brendan;
    Score = 10;
    UUID = "BD561F1C-72A8-4A01-A71A-850682E49D61";
;
"-KC3MktbOyltGaJZ_XtD" =     
    ".priority" = "-10";
    Date = "1457140993.694163";
    Name = brendan;
    Score = 10;
    UUID = "BD561F1C-72A8-4A01-A71A-850682E49D61";
;
"-KC3MktjFj6VVAJfitZp" =     
    ".priority" = "-10";
    Date = "1457140993.701368";
    Name = brendan;
    Score = 10;
    UUID = "BD561F1C-72A8-4A01-A71A-850682E49D61";
;
"-KC3Mktk0_f6_eM8wP1x" =     
    ".priority" = "-10";
    Date = "1457140993.702492";
    Name = brendan;
    Score = 10;
    UUID = "BD561F1C-72A8-4A01-A71A-850682E49D61";
;
"-KC3MktrZaStt9b5pID_" =     
    ".priority" = "-10";
    Date = "1457140993.709843";
    Name = brendan;
    Score = 10;
    UUID = "BD561F1C-72A8-4A01-A71A-850682E49D61";
;
"-KC3QALPl38gbDy4xLE2" =     
    ".priority" = "-10";
    Date = "1457141888.477473";
    Name = brendan;
    Score = 10;
    UUID = "BD561F1C-72A8-4A01-A71A-850682E49D61";
;
"-KC3qGAqZiJ9Vs40MwG7" =     
    ".priority" = "-10";
    Date = "1457148990.24583";
    Name = brendan;
    Score = 10;
    UUID = "BD561F1C-72A8-4A01-A71A-850682E49D61";
;

这是我在 print(json) 行中排序不正确的数据：

  "-KC3MktrZaStt9b5pID_" : 
    "Score" : "10",
    "UUID" : "BD561F1C-72A8-4A01-A71A-850682E49D61",
    "Date" : 1457140993.709843,
    "Name" : "brendan"
  ,
  "-KC3QALPl38gbDy4xLE2" : 
    "Score" : 10,
    "UUID" : "BD561F1C-72A8-4A01-A71A-850682E49D61",
    "Date" : 1457141888.477473,
"Name" : "brendan"
  ,
  "-KC3MktW0iJfkAKjlCy4" : 
    "Score" : "9",
    "UUID" : "BD561F1C-72A8-4A01-A71A-850682E49D61",
    "Date" : 1457140993.686348,
    "Name" : "brendan"
  ,
  "-KC3MktbOyltGaJZ_XtD" : 
    "Score" : "10",
    "UUID" : "BD561F1C-72A8-4A01-A71A-850682E49D61",
    "Date" : 1457140993.694163,
    "Name" : "brendan"
  ,
  "-KC3Mktk0_f6_eM8wP1x" : 
    "Score" : "10",
    "UUID" : "BD561F1C-72A8-4A01-A71A-850682E49D61",
    "Date" : 1457140993.702492,
    "Name" : "brendan"
  ,
  "-KC3MktM-rWmoitem8na" : 
    "Score" : "9",
    "UUID" : "BD561F1C-72A8-4A01-A71A-850682E49D61",
    "Date" : 1457140993.677347,
    "Name" : "brendan"
  ,
  "-KC3MktapH6Mebw2sAUe" : 
    "Score" : "10",
    "UUID" : "BD561F1C-72A8-4A01-A71A-850682E49D61",
    "Date" : 1457140993.692581,
    "Name" : "brendan"
  ,
  "-KC3qGAqZiJ9Vs40MwG7" : 
    "Score" : 10,
    "UUID" : "BD561F1C-72A8-4A01-A71A-850682E49D61",
    "Date" : 1457148990.24583,
    "Name" : "brendan"
  ,
  "-KC3MktjFj6VVAJfitZp" : 
    "Score" : "10",
    "UUID" : "BD561F1C-72A8-4A01-A71A-850682E49D61",
    "Date" : 1457140993.701368,
    "Name" : "brendan"
  ,
  "-KC3MktE1jS5z9-tTEgJ" : 
    "Score" : "9",
    "UUID" : "BD561F1C-72A8-4A01-A71A-850682E49D61",
    "Date" : 1457140993.669797,
    "Name" : "brendan"
  

由于我使用 json 对象来获取键，从而填充数组，因此数组中的数据是乱序的。

我错过了什么？

【问题讨论】：

JSON 字典键未排序。会不会是这个问题？

这里有几件事。 Firebase 的顺序概念由您定义；您需要一个密钥来让 Firebase 在读入数据时知道如何对其进行排序。如果您想要一个按时间顺序排列的顺序，那么 .orderBy 时间戳。如果你想按分数排序，那么 .orderBy 分数。不要假设您的 Firebase 数据会被排序 - 它们可能是按键排序的，但这可能不是您想要的。要正确回答问题，请定义您希望数据排序的方式，我们将向您展示如何实现。

【参考方案1】：

如果您想保持顺序，请使用数组而不是字典，无论是 JSON 还是 Swift 对象。所以为了保持排序，你可以改变你的JSON结构：

  "-KC3MktrZaStt9b5pID_" : 
    "Score" : "10",
    "UUID" : "BD561F1C-72A8-4A01-A71A-850682E49D61",
    "Date" : 1457140993.709843,
    "Name" : "brendan"
  ,
  "-KC3QALPl38gbDy4xLE2" : 
    "Score" : 10,
    "UUID" : "BD561F1C-72A8-4A01-A71A-850682E49D61",
    "Date" : 1457141888.477473,
    "Name" : "brendan"
  

到这里：

[
  
    "Key": "-KC3MktrZaStt9b5pID_",
    "Score": "10",
    "UUID": "BD561F1C-72A8-4A01-A71A-850682E49D61",
    "Date": 1457140993.709843,
    "Name": "brendan"
  ,
  
    "Key": "-KC3QALPl38gbDy4xLE2",
    "Score": 10,
    "UUID": "BD561F1C-72A8-4A01-A71A-850682E49D61",
    "Date": 1457141888.477473,
    "Name": "brendan"
  
]

【讨论】：

我不认为 Firebase 本身支持数组，根据：firebase.com/blog/…

好的，然后保留你的旧语法。博客中关于使用优先级对数据进行排序的部分可能很方便，字典本身没有排序。

@jakhamma NSArray 在 Firebase 中绝对受支持。但是，大多数时候有比使用数组存储数据更好的解决方案。数组可能......有问题，应该只在特定情况下使用，即使这样通常也有更好的选择。