我是Firebase的新手,也是我将项目从Parse切换到Firebase的过程.

示例：我在Firebase中有一个如下所示的数据：

我可以抓住Swift中的所有主题：

let refDB  = FIRDatabase.database().reference(fromURL: firebaseDB_URL)
    let topicsRef = refDB.child("topics")
    // FIRDataSnapshot.
    topicsRef.observe(.value,with: { snapshot in
        for child in snapshot.children {
            print("child ------")
            print(child)
            // Get the bits  HOW DO I PARSE EACH SET

        }
    })

当我遍历for循环时,我会打印出如下所示的内容：

child ------
Snap (-KYCqk2_AVkUd8s9cKit) {
    createdBy = FeMFeedat4VZb5tmFO2tKixgQIy1;
    description = "Match states with their capitals";
    name = "State Caiptals";
    tags =     {
        0 = Geography;
        1 = USA;
    };
}

child ------
Snap (-KYCqk2_AVkUd8s9cKiu) {
    createdBy = FeMFeedat4VZb5tmFO2tKixgQIy1;
    description = "Name the parts of an Atom";
    name = "Parts of an Antom";
    tags =     {
        0 = Physics;
        1 = Atom;
        2 = Electron;
    };
}

我的问题是,我如何获得数据：

我需要钥匙(KYCqk2_AVkUd8s9cKiu)
我需要描述和名称
我需要一系列标签

– 所有局部变量？

基本上,我只想阅读所有主题,并在本地内存中有一系列主题.

我可以负责构建Class主题的数组,但我已经尝试了几种方法来获取数据而没有运气.必须有一种简单的方法来解析结果,但我没有找到示例或文档.

希望得到一些帮助或指向某些文档或教程的指针.

=================================

更新的代码

嗨我改变了代码以尝试匹配提供的样本.代码现在如下所示
我放入一个循环计数器,看看发生了什么以及为什么会崩溃.

FDataSnapshot未定义,因此我使用了FIRDataSnapshot.

这是对代码的新尝试,现在崩溃了.在下面我展示我的更改,使其不崩溃 – 以及关于安全地处理标签子节点的问题.谢谢你的指针.我现在有一些有用的东西.

// HERE is a way to get all the Topics
let refDB  = FIRDatabase.database().reference(fromURL: firebaseDB_URL)
let topicsRef = refDB.child("topics")
// FIRDataSnapshot.
topicsRef.observe(.value,with: { snapshot in

    if snapshot.value is NSNull {
        print("not found")
    } else {
        var loopCount = 1  //  count loops to see how may time trying to loop
        for child in snapshot.children {

            print("            ")
            print("            ")
            print("child ------ loop \(loopCount)")
            print(child)

            let snap = child as! FIRDataSnapshot //each child is a snapshot
            let dict = snap.value as! [String: String] // the value is a dictionary
            let name = dict["name"]!
            let description = dict["description"]!
            let createdBy = dict["createdBy"]!
            print("the bits ------")
            print("name .... \(name)")
            print("description .... \(description)")
            print("createdBy .... \(createdBy)")
            loopCount += 1

        }
    }
})

我定义了零断点 – 但是代码在此断点处停止(当我确定零断点时)

libswiftCore.dylib`_swift_bridgeNonVerbatimFromObjectiveC:
    0x1144a4270 <+0>:   pushq  %rbp
    0x1144a4271 <+1>:   movq   %rsp,%rbp
    0x1144a4274 <+4>:   pushq  %r15

…在这里打破三次,然后应用程序在此行崩溃
让dict = snap.value为！ [String：String]
消息“线程1：EXC_BAD_INSTRUCTION(代码= EXEC_1386_INVOP,subside = 0x0)

我不确定为什么代码有断点以及它崩溃的原因.点击标签时可能会崩溃,因为标签是子节点并且不适合[String,String]

我在日志中打印这个然后去繁荣！

child ------ loop 1
Snap (-KYI2MszjC9pK_4oIvKu) {
    createdBy = FeMFeedat4VZb5tmFO2tKixgQIy1;
    description = "Match states with their capitals";
    name = "State Caiptals";
    tags =     {
        0 = Geography;
        1 = USA;
    };
}

=====

如果我改变线以使用’任何’….那么它的工作原理

let dict = snap.value as! [String: Any]

新的工作代码….

// HERE is a way to get all the Topics
let refDB  = FIRDatabase.database().reference(fromURL: firebaseDB_URL)
let topicsRef = refDB.child("topics")
// FIRDataSnapshot.
topicsRef.observe(.value,with: { snapshot in

    if snapshot.value is NSNull {
        print("not found")
    } else {
        var loopCount = 1  //  count loops to see how may time trying to loop
        for child in snapshot.children {

            print("            ")
            print("            ")
            print("child ------ loop \(loopCount)")

            let snap = child as! FIRDataSnapshot //each child is a snapshot

            if snap.value != nil {
                print("key ... \(snap.key)")
                let dict = snap.value as! [String: Any] // the value is a dictionary
                let name = dict["name"] as! String
                let description = dict["description"] as! String
                let createdBy = dict["createdBy"] as! String
                let tags = dict["tags"] as! NSArray  

                /* Thought I could loop tags as! Dictionary but that does not work. Compiles but runtime crashes.
                var tagsArray = [String]()
                if tags != nil && tags.count > 0 {
                    for (key,value) in tags {
                        tagsArray.append(value)
                    }
                } */

                // Test to see what we got ...
                print("the bits ------")
                print("name .... \(name)")
                print("description .... \(description)")
                print("createdBy .... \(createdBy)")
                print("tags ... \(tags)  ... count \(tags.count)")
                loopCount += 1
            } else {
                print("bad snap")
            }

        }
    }
})

我从其他响应发送的doc链接中找出了主题密钥.谢谢.

我不确定我是否正确获取了标签值.它实际上只是一个字典而且我试图以这种方式进行转换,但是运行时崩溃并希望将标签转换为NSArray ….所以我在代码中执行了它并且它可以工作但不确定这是否安全,因为这不是定义为数组,即使它作为数组返回.