ios - 如何将 Firebase 快照中的变量分配给子节点中的值？

Question

我正在尝试尽量减少向 Firebase 发出的数据请求量。我有一个提取以下数据的快照:

snap (Hole1) {
GreenBackX = "40.196339";
GreenBackY = "-105.07354";
GreenCenterX = "40.196336";
GreenCenterY = "-105.073409";
GreenFrontX = "40.196342";
GreenFrontY = "-105.073283";
Hazard1 =     {
    CarryX = "40.196839";
    CarryY = "-105.07104";
    FrontX = "40.196893";
    FrontY = "-105.070626";
    Name = "R Fwy Bunker";
};
Hazard2 =     {
    CarryX = "40.196321";
    CarryY = "-105.071922";
    FrontX = "40.196383";
    FrontY = "-105.071573";
    Name = "L Fwy Bunker";
};
Hazard3 =     {
    CarryX = "40.196622";
    CarryY = "-105.072935";
    FrontX = "40.196662";
    FrontY = "-105.072554";
    Name = "R Fwy Bunker 2";
};
Hazard4 =     {
    CarryX = "40.196176";
    CarryY = "-105.073545";
    FrontX = "40.196225";
    FrontY = "-105.073167";
    Name = "L Greenside Bunker";
};
HoleH = "258.74";
HoleX = "40.19664";
HoleY = "-105.070484";
}

我的目标是分配一个变量，即Hazard1\Name。到目前为止，我只在文档中看到了工作示例，展示了如何获取初始值，我喜欢这样: letholeX = value?["HoleX"] as?双倍的 ？？ 0，但如果你愿意的话，我似乎找不到任何能让我达到“第二级”的东西。

有一个示例似乎表明您可以通过以下方式引用它来做到这一点:let Hazard1Name = value?["Hazard1/Name"] 但我无法让它工作。

Answer 1

FIRDataSnapshot 包含来自给定 Firebase 数据库位置的数据。数据已经下载完毕，因此没有太多优化空间，抱歉:-(

我认为您可能正在寻找的是:

let ref: FIRDatabaseReference = ...
ref.child("Hazard1").child("Name").observeSingleEvent(of: .value) {
    (snapshot) in
    let name = snapshot.value as! String
    print("Name: \(name)")
}

否则，如果您只是想要从上述快照中获取数据，请尝试以下操作:

let snapshot: FIRDataSnapshot = ...
let data = snapshot.value as! [String: Any]
let hazard1 = data["Hazard1"] as! [String: Any]
let name = hazard1["Name"] as! String