如何从 Swift 4/json 字典中的多值键中检索单个值？

Question

检索键值的例子有很多，我可以做到。在这种情况下，键有多个值。关键是“挖矿”，后面跟着6个值。同一个 key:value 重复 30 次，当然 key 的值不同。

我似乎无法解决的是如何返回值。尤其是第一个，例如 1532825277682891390，它似乎是一个带有与其相关的键/值对的子键。

The todo is: ["mining": {
1532825277682891390 =     {
    command = mining;
    siteid = "Platform Mining";
    ts = 1532825270557;
    user1 = 73276;
    value = 1;
};
1532826406100318457 =     {
    command = mining;
    siteid = "Platform Mining";
    ts = 1532826375712;
    user1 = 73276;
    value = 1;
};
1532827074955562013 =     {
    command = mining;
    siteid = "Platform Mining";
    ts = 1532827066645;
    user1 = 73276;
    value = 1;
};
153282775791322835 =     {
    command = mining;
    siteid = "Platform Mining";
    ts = 1532827753205;
    user1 = 73276;
    value = 1;
};

....
....
....
}

我可以显示“挖掘”键的键：值。字典里只有两个键，'mining'和'success'——我不担心'success'，它通常返回'1'。

这基本上是带有一些示例和试验输出的代码，因为我尝试了与其他帖子不同的东西。我只是无法理解这一点。 我是否需要将字典放入数组中，我该怎么做，或者我可以将每个值放入 var 中，这样我就可以将它们打印到 UITabDisplay 中？

    func makeGetCall() {
    // Set up the URL request
    let todoEndpoint: String = "https://api.jsecoin.com/v1.7/mining/auth/"

    let apiKey = "xxxxxxxxxxxxxxxxxxxxxxx"


    guard let url = URL(string: todoEndpoint) else {
        print("Error: cannot create URL")
        return
    }
    var urlRequest = URLRequest(url: url)

    urlRequest.setValue(apiKey, forHTTPHeaderField: "Authorization")
    urlRequest.setValue("application/json", forHTTPHeaderField: "Content-Type")
    // set up the session
    let config = URLSessionConfiguration.default
    let session = URLSession(configuration: config)

    // make the request
    let task = session.dataTask(with: urlRequest) {
        (data, response, error) in
        // check for any errors
        guard error == nil else {
            print("error calling GET on /todos/1")
            print(error!)
            return
        }


        // make sure we got data
        guard let responseData = data else {
            print("Error: did not receive data")
            return
        }
        print("Got data: \(responseData)")
        // parse the result as JSON, since that's what the API provides
        do {
            guard let todo = try JSONSerialization.jsonObject(with: responseData, options: [])
                as? [String: Any] else {
                    print("error trying to convert data to JSON")
                    return
            }
            // now we have the todo
            // let's just print it to prove we can access it
           print("The todo is: " + todo.description)

           // from this point on I"m experimenting ....

            let dict = todo.description
            print("The dict is: " + dict)

            let keys = Array(todo.keys)
            // prints ["mining", "success"]
            print(keys)
            /////////////////////////////////
            if let alb = todo["mining"] {
                // prints all the values for 'mining'.
               //  {
               //   1532825277682891390 =     {
               //   command = mining;
               //   siteid = "Platform Mining";
               //   ts = 1532825270557;
              //    user1 = 73276;
              //    value = 1;
             //    };
             // ........ 30 entires
                print(alb)
            }
            //======================
            let index1 = todo.index(forKey: "mining")
            let myMining = (todo[index1!].value)

            // again prints all the mining values. Mining: {
            // 1532825277682891390 =     {
            // command = mining;
            // siteid = "Platform Mining";
            // ts = 1532825270557;
            // user1 = 73276;
            // value = 1;
            // };

            print("Mining: \(myMining)")

            //============ 

Answer 1

您可以按照您为获取 todo 字典的键而编写的类似方式进行操作。

if let mining = todo["mining"] as? [String: Any] {
   let miningKeys = Array(mining.keys)
   // It will be like [1532825277682891390, 1532826406100318457]
}

使用miningKeys 访问该挖掘字典中的值，例如：

mining[miningKeys.first!]
// It will return
// {
//   command = mining;
//   siteid = "Platform Mining";
//   ts = 1532825270557;
//   user1 = 73276;
//   value = 1;
// }

Answer 2

键 mining 的值是一个字典。有条件地将alb 向下转换为预期类型并枚举字典

if let alb = todo["mining"] as? [String:Any] {
    for (key, value) in alb {
        print(key, value)
    }
}

如果你想单独打印内部字典的每个键值对，你可以使用

if let alb = todo["mining"] as? [String:Any] {
    for (key, mining) in alb {
        print(key)
        if let item = mining as? [String:Any] {
           for (key, value) in item {
               print(key, value)
           }
        }
    }
}

请注意，for 循环中的 keys 不能保证与 JSON 中的顺序相同。