JSON 在 swift 中响应解码为 nil

Question

struct Jresponse: Decodable{
            //var results: [Any]
            var resolution: Int?
            var elevation:  Int?
            var location: Int?
            var lat: Int?
            var lng: Int?
        }
        guard let url = URL(string: "https://maps.googleapis.com/maps/api/elevation/json?&locations=\(finalStringConvertedCoordinates)&key=\(apiKey)") else {
                    print("Error: cannot create URL")
                    return
                }
                // Create the url request
                var request = URLRequest(url: url)
                request.httpMethod = "GET"
                URLSession.shared.dataTask(with: request) { data, response, error in
                    guard error == nil else {
                        print("Error: error calling GET")
                        print(error!)
                        return
                    }
                    guard let data = data else {
                        print("Error: Did not receive data")
                        return
                    }
                    guard let response = response as? HTTPURLResponse, (200 ..< 299) ~= response.statusCode else {
                        print("Error: HTTP request failed")
                        return
                    }
                    do {
                        guard let jsonObject = try JSONSerialization.jsonObject(with: data) as? [String: Any] else {
                            print("Error: Cannot convert data to JSON object")
                            return
                        }
                        guard let prettyJsonData = try? JSONSerialization.data(withJSONObject: jsonObject, options: []) else {
                            print("Error: Cannot convert JSON object to Pretty JSON data")
                            return
                        }
                        guard let prettyPrintedJson = String(data: prettyJsonData, encoding: .utf8)
                        else {
                            print("Error: Could print JSON in String")
                            return
                        }
                        //print(prettyPrintedJson)
                        jsonResponse = prettyPrintedJson
                    } catch {
                        print("Error: Trying to convert JSON data to string")
                        return
                    }
                    let decoder = JSONDecoder()
                    let jrData = jsonResponse.data(using: .utf8)
                    let jsonResponseProcessed = try! decoder.decode(Jresponse.self, from: jrData! )
                    print(jsonResponseProcessed)
                }.resume()
        
            }

上面的代码包含请求和响应的解码，我对 JSON 没有经验，这可能很明显。

我遇到的问题是打印时返回的结果都是零。

以前我没有使用解码，而是试图将数据处理成一个数组，在该数组中可以检索各个值以进行比较。

数组方法生成难以管理的数据，因为元素未按可管理的顺序分隔。

像这样[无响应][1]

包含 print("---> data: (String(data: data, encoding: .utf8))") 的输出看起来像这样。

[输出可以在这里看到][2]

---> data: Optional("{\n "results" : [\n {\n "elevation" : 11.59268283843994,\n "location" : {\n "lat" : 37.78533554077148,\n "lng" : -122.4059982299805\n },\n "resolution" : 0.5964969992637634\n },\n {\n "elevation" : 11.68190288543701,\n "location" : {\n " lat" : 37.78538513183594,\n "lng" : -122.4059143066406\n },\n "resolution" : 0.5964969992637634\n },\n {\n "elevation" : 11.86490249633789,\n " location" : {\n "lat" : 37.78548812866211,\n "lng" : -122.4059143066406\n },\n "resolution" : 0.5964969992637634\n },\n {\n "海拔" : 11.53255939483643,\n "location" : {\n "lat" : 37.78533554077148,\n "lng" : -122.4061584472656\n },\n "resolution" : 0.5964969992637634\n }, \n {\n “海拔”：11.46291351318359，\n “位置”：{\n “纬度”：37.78533554077148，\n “经度”：-12 2.4063262939453\n },\n "resolution": 0.5964969992637634\n },\n {\n "elevation": 11.69645023345947,\n "location": {\n "lat": 37.78558731079102, \n“lng”：-122.4059143066406\n}，\n“分辨率”：0.5964969992637634\n}，\n{\n“海拔”：11.79109859466553，\n“位置”：{\ n "lat" : 37.78569030761719,\n "lng" : -122.4059143066406\n },\n "resolution" : 0.5964969992637634\n },\n {\n "elevation" : 11.357332222961426,\ n "location" : {\n "lat" : 37.78533554077148,\n "lng" : -122.4064865112305\n },\n "resolution" : 0.5964969992637634\n },\n {\n “海拔”：11.57364559173584，\n “位置”：{\n “纬度”：37.78533554077148，\n “经度”：-122.4066467285156\n }，\n “分辨率”：0.5964969992637634\n },\n {\n “海拔”：11.7429027557373，\n “位置”：{\n “纬度”：37.78578948974609，\n "lng" : -122.4059143066406\n },\n "resolution" : 0.5964969992637634\n },\n {\n "elevation" : 12.02133083343506,\n "location" : {\n " lat" : 37.78589248657227,\n "lng" : -122.4059143066406\n },\n "resolution" : 0.5964969992637634\n },\n {\n "elevation" : 11.66207313537598,\n " location" : {\n "lat" : 37.78533554077148,\n "lng" : -122.4068145751953\n },\n "resolution" : 0.5964969992637634\n },\n {\n "海拔" : 11.85497093200684,\n "location" : {\n "lat" : 37.78536987304688,\n "lng" : -122.4069137573242\n },\n "resolution" : 0.5964969992637634\n }, \n {\n “海拔”：12.22011947631836，\n “位置”：{\n “纬度”：37.78599548339844，\n “经度”：-122.4059143066406\n }，\n “分辨率”：0。 5964969992637634\n },\n {\n "海拔": 12.59670543670654,\n "位置": {\n "纬度": 37.78609466552 734,\n "lng": -122.4059143066406\n },\n "分辨率": 0.5964969992637634\n },\n {\n "海拔": 12.19275951385498,\n "位置": {\n "lat" : 37.78546905517578,\n "lng" : -122.4069137573242\n },\n "resolution" : 0.5964969992637634\n },\n {\n "elevation" : 12.13292598724365 ,\n "location" : {\n "lat" : 37.78557205200195,\n "lng" : -122.4069137573242\n },\n "resolution" : 0.5964969992637634\n },\n { \n“海拔”：12.98763847351074，\n“位置”：{\n“lat”：37.78619766235352，\n“lng”：-122.4059143066406\n}，\n“分辨率”：0.5964969992637634\n },\n {\n "海拔": 13.3654317855835,\n "位置": {\n "纬度": 37.78629684448242,\n "经度": -122.4059143066406\n },\n "分辨率" : 0.5964969992637634\n },\n {\n "海拔": 12.14237785339355,\n "位置": {\n "lat" : 37.78567504882812,\n "lng": -122.4069137573242\n },\n "分辨率": 0.5964969992637634\n },\n {\n "海拔": 12.26948738098145,\n "位置": {\n "lat" : 37.78577423095703,\n "lng" : -122.4069137573242\n },\n "resolution" : 0.5964969992637634\n },\n {\n "elevation" : 13.74397277832031 ,\n "location" : {\n "lat" : 37.78633499145508,\n "lng" : -122.4060211181641\n },\n "resolution" : 0.5964969992637634\n },\n { \n“海拔”：14.1032075881958，\n“位置”：{\n“纬度”：37.78633499145508，\n“经度”：-122.4061889648438\n}，\n“分辨率”：0.5964969992637634\n },\n {\n "海拔": 12.31325626373291,\n "位置": {\n "纬度": 37.7858772277832,\n "经度": -122.4069137573242\n },\n "分辨率" : 0.5964969992637634\n },\n {\n "海拔": 12.36202812194824,\n "位置": {\n "lat" : 37.78598022460938,\n "lng" : -122.4069137573242\n },\n "resolution" : 0.5964969992637634\n },\n {\n "elevation" : 14.12999248504639,\n "location" : {\n "lat" : 37.78633499145508,\n "lng" : -122.4063491821289\n },\n "resolution" : 0.5964969992637634\n },\n {\n "高程”：14.4321174621582，\n “位置”：{\n “lat”：37.78633499145508，\n “lng”：-122.4065093994141\n }，\n “分辨率”：0.5964969992637634\n } ,\n {\n "海拔": 12.53042221069336,\n "位置": {\n "纬度": 37.78607940673828,\n "经度": -122.4069137573242\n },\n "分辨率": 0 .5964969992637634\n },\n {\n "海拔": 13.14097881317139,\n "位置": {\n "纬度": 37.78618240356445,\n "经度": -122.4069137573242\n }, \n "resolution" : 0.5964969992637634\n },\n {\n "elevation" : 14.39413261413574,\n "location " : {\n "lat" : 37.78633499145508,\n "lng" : -122.4066696166992\n },\n "分辨率" : 0.5964969992637634\n },\n {\n "海拔" : 14.40865802764893,\n "location" : {\n "lat" : 37.78633499145508,\n "lng" : -122.4068374633789\n },\n "resolution" : 0.5964969992637634\n },\ n {\n “海拔”：13.98401737213135，\n “位置”：{\n “纬度”：37.78628158569336，\n “经度”：-122.4069137573242\n }，\n “分辨率”：0.5964969992637634\n }\n ],\n "状态" : "OK"\n}\n") Jresponse（分辨率：无，高程：无，位置：无，纬度：无，经度：无） [1]: https://i.stack.imgur.com/uaRZZ.png [2]: https://i.stack.imgur.com/MWJZX.png

Answer 1

根据@Joakim Danielson 的建议，您应该将代码修改为

 let jsonResponseProcessed = try! decoder.decode(Jresponse.self, from: data )

根据 google 文档，位于：https://developers.google.com/maps/documentation/elevation/start

你应该使用这个数据结构：EDIT

struct Jresponse: Codable {
    let results: [Result]
    let status: String?
}

struct Result: Codable {
    let elevation: Double
    let location: Location
    let resolution: Double?
}

struct Location: Codable {
    let lat, lng: Double
}

Answer 2

解码失败

您无法获取任何数据的最可能原因是您的数据模型（此处定义为结构 Jresponse）不符合后端发回的实际 JSON 格式。

我已经快速检查了 google 地图 api 文档的海拔高度，您似乎应该收到一个 json 对象，其中包含顶层的 ElevationResult 数组。然后每个结果将包含分辨率、海拔和位置。

请参考https://developers.google.com/maps/documentation/elevation/overview#ElevationResult

正确的数据模型


struct ElevationResponse: Decodable {
    let results: [ElevationResult]
}

struct ElevationResult: Decodable {
     let elevation: Double
     let location: LatLngLiteral
     let resolution: Double?
}

struct LatLngLiteral: Decodable {
     let lat: Double
     let lng: Double
}

更改解码中的模型

let jsonResponseProcessed = try! decoder.decode(ElevationResponse.self, from: data)

边注

解码数据的方式可以更现代化和更清洁
注意不要使用force unwrap和force try
发布您的问题时，请注意代码缩进，首先 select 您在 Xcode 中的代码，然后执行 ctrl + i 以提高其可读性。然后才将其复制到您的 Whosebug 问题中。

JSON 在 swift 中响应解码为 nil

JSON response decoding to nil in swift

json

swift

httprequest

google-elevation-api

解码失败

正确的数据模型

更改解码中的模型

边注