Question

我正在使用一个数据结构，我循环遍历几个节点，这是我得到的json数据。

Snap (20171012) {
"-KwM45HyW4UduQgKTGn6" =     {
    ImageName = "Screen Shot 2017-10-13 at 11.24.51 AM.png";
    fileURL = "";
    thumbFileUrl = "";
    user = "User not defined";
};
"-KwM4limD2aRyHgeKE5P" =     {
    ImageName = "test.png";
    fileURL = "";
    thumbFileUrl = "";
    user = "User not defined";
};

}

在此之后，我可以访问＆＃34; snap＆＃34;使用我的data.key来获得＆＃34; 20171012＆＃34;

ref.child(myselected_spot!).observe(DataEventType.value, with: { (snapshot) in
        if snapshot.childrenCount > 0 {
            for mydata in snapshot.children.allObjects as! [DataSnapshot]
            {
                if mydata.key.characters.count == 8 {
                self.formattedDates.append(convertDate(stringDate: mydata.key))
                self.selected_dates.append(mydata.key)

我如何获得＆＃34; ImageName＆＃34;

的值

Answer 1

您的mydata是另一个DataSnapshot，因此您可以访问all methods and properties of that class。在这种情况下，您正在寻找DataSnapshot.childSnapshotForPath:：

ref.child(myselected_spot!).observe(DataEventType.value, with: { (snapshot) in        if snapshot.childrenCount > 0 {
    for mydata in snapshot.children.allObjects as! [DataSnapshot]
    {
        if mydata.key.characters.count == 8 {
        self.formattedDates.append(convertDate(stringDate: mydata.key))
        self.selected_dates.append(mydata.key)
        print(mydata.childSnapshot(forPath: "ImageName").value)

Answer 2

非常简单 - 我不知道变量myselected_Spot是什么，但我会假设-KwM45HyW4UduQgKTGn6。如果下面的代码没有产生结果 - 我将需要知道该变量是什么。

ref.child(myselectd_spot).observe(.value, with: { (snapshot) in
    if snapshot.value is NSNull{
        //handles errors
        return
    }
    else{
        if let selectedSnapDict = snapshot.value as? NSDictionary {//Can also be [String: Any]
            print(selectedSnapDict["ImageName"] as! String) //We know it's a string
        }
        else{
            //null
        }
    }
})

在swift中访问嵌套的firebase数据

2 个答案: