json - 如何使用 SWIFT 3 提取嵌套 JSON 中的第一个重复元素

Question

我正在尝试从以下 JSON 中提取第一个 "Field1" 和 "Field2" 值:

{
"channel": {
    "id": 297681,
    "name": "Basement",
    "description": "Climate Node Upstairs",
    "latitude": "0.0",
    "longitude": "0.0",
    "field1": "Temperature",
    "field2": "Humidity",
    "created_at": "2017-07-04T21:43:23Z",
    "updated_at": "2017-07-30T16:52:48Z",
    "last_entry_id": 17803
},
"feeds": [
    {
        "created_at": "2017-07-30T16:50:46Z",
        "entry_id": 17802,
        "field1": "68.18",
        "field2": "53.80"
    },
    {
        "created_at": "2017-07-30T16:52:48Z",
        "entry_id": 17803,
        "field1": "68.18",
        "field2": "53.90"
    }
]
}

我有以下工作代码，可以打印两个提要的文本:

  let url = URL(string: "https://api.thingspeak.com/channels/297681/feeds.json?api_key=xxxx&results=2")!

    let task = URLSession.shared.dataTask(with: url)
    {
        (data, response, error)
        in
        if let data = data, let rawJSON = try? JSONSerialization.jsonObject(with: data, options:.allowFragments) as? [String: Any]
        {
            print ("rawjason set")

            if let json = rawJSON as? [String: Any]
            {
                //print(json) //should print json
                //  print("<-------->`")
                //  print(json["channel"])
                let channel = json["channel"] as! [String: Any]
                // print(channel["name"]!)

                //let locname = channel["name"]! as! [String: String]
                let locname = channel["name"]!
                print("<-- name next -->")
                print(locname)


                let feeds = json["feeds"]
                print("<feeds>")
                print(feeds)

但是，当我尝试提取第一个提要条目时，我所做的尝试不起作用。

我已经尝试过:

//fails with Type Any> has no subscript members:
let feed1 = feeds[0]

抱歉，如果之前已经介绍过这一点，我在堆栈溢出上查看了几个类似的问题，但无法使它们适应我的情况。

Answer 1

由于 json 的类型为 Any，因此您需要将其转换为更具体的类型，即字典数组。

if let feeds = json["feeds"] as? [[String:Any]] {
    for feed in feeds {
        if let field1 = feed["field1"] as? Double {
            //do whatever you need to with field1
        }
        if let field2 = feed["field2"] as? Double {
            //do whatever you need to with field2
        }
    }
}