ios - 更正可编码结构 Swift 4 和 KeyNotFound 错误

Question

已编辑

您好，我是第一次使用可编码协议(protocol):我的 JSON 响应(使用 POSTMAN)是:

[
{
    "FltId": "928",
    "Carrier": "AS",
    "Orig": "ANC",
    "Dest": "SEA",
    "CutOffTime": "40",
    "FltDirection": 0,
    "SchedDepTime": "2018-03-21T01:25:00",
    "EstDepTime": "2018-03-21T01:25:00",
    "SchedArrTime": "2018-03-21T05:43:00",
    "EstArrTime": "2018-03-21T05:43:00",
    "ActualTime": "",
    "OrigZuluOffset": "-8",
    "DestZuluOffset": "-7",
    "DestGate": "C15",
    "OrigGate": "",
    "CodeShares": [
        {
            "FltId": "",
            "Carrier": ""
        }
    ],
    "TailId": "251",
    "FleetType": "737-900R",
    "Status": "ON TIME"
},
{
    "FltId": "3422",
    "Carrier": "OO",
    "Orig": "BLI",
    "Dest": "SEA",
    "CutOffTime": "40",
    "FltDirection": 0,
    "SchedDepTime": "2018-03-21T05:00:00",
    "EstDepTime": "2018-03-21T05:00:00",
    "SchedArrTime": "2018-03-21T05:56:00",
    "EstArrTime": "2018-03-21T05:56:00",
    "ActualTime": "",
    "OrigZuluOffset": "-7",
    "DestZuluOffset": "-7",
    "DestGate": "C16",
    "OrigGate": "",
    "CodeShares": [
        {
            "FltId": "",
            "Carrier": ""
        }
    ],
    "TailId": "417",
    "FleetType": "CRJ-200",
    "Status": "ON TIME"
}]

我在我的 swift 代码中创建了一个可编码的对象结构，想知道它是否正确:

struct Response: Codable {
    let flights: [Flight]
}

struct Flight: Codable{
    let FltId, Carrier, Orig, Dest, CutOffTime, FltDirection, SchedDepTime, EstDepTime, SchedArrTime, EstArrTime, ActualTime, OrigZuluOffset, DestZuluOffset, DestGate, OrigGate, TailId, FleetType, Status: String, CodeShares:[CodeShare]
}
struct CodeShare: Codable {
    let FltId, Carrier: String
}

这是否可以进一步修复或改进？此外什么是编码键？我收到这个奇怪的错误:

失败(Swift.DecodingError.keyNotFound(table_view_api.FlightWebService.Response。(_954486EAAC5BB7DDCEFC26E493D69F38 中的 CodingKeys)。航类，Swift.DecodingError.Context(编码路径:[基础。(_12768CA107A31EF2DCE034FD7 中的 _JSONKey)(字符串 541FD7 中的 _JSONKey) ", intValue: Optional(0))], debugDescription: "No value associated with key flights (\"flights\").", underlyingError: nil)))

我错过了什么吗？

此外，我正在使用正确的身份验证 header 发出我的网络服务请求，例如:

var request = URLRequest(url: url)
    request.httpMethod = "GET"
    request.setValue("Basic YWFnZTQxNDAxMjgwODYyNDk3NWFiYWNhZjlhNjZjMDRlMWY6ODYyYTk0NTFhYjliNGY1M2EwZWJiOWI2ZWQ1ZjYwOGM=", forHTTPHeaderField: "Authorization")



func getFlightData(for airportCode: String, minutesBehind:String, minutesAhead:String, completion: ((Result<[Response]>) -> Void)?) {
    var urlComponents = URLComponents()
    urlComponents.scheme = "https"
    urlComponents.host = "api.qa.alaskaair.com"
    urlComponents.path = "/1/airports/"+airportCode+"/flights/flightInfo"
    urlComponents.queryItems = [
        URLQueryItem(name: "city", value: airportCode),
        URLQueryItem(name: "minutesBehind", value: minutesBehind),
        URLQueryItem(name: "minutesAhead", value: minutesAhead)

    ]

    guard let url = urlComponents.url else { fatalError("Could not create URL from components") }

    var request = URLRequest(url: url)
    request.httpMethod = "GET"
    request.setValue("Basic YWFnZTQxNDAxMjgwODYyNDk3NWFiYWNhZjlhNjZjMDRlMWY6ODYyYTk0NTFhYjliNGY1M2EwZWJiOWI2ZWQ1ZjYwOGM=", forHTTPHeaderField: "Authorization")

    let config = URLSessionConfiguration.default
    let session = URLSession(configuration: config)
    let task = session.dataTask(with: request) { (responseData, response, responseError) in
        DispatchQueue.main.async {
            if let error = responseError {
                completion?(.failure(error))
            } else if let jsonData = responseData {

                let decoder = JSONDecoder()

                do {

                    let posts = try decoder.decode(Array<Flight>.self, from: jsonData)
                    completion?(.success(posts))
                } catch {
                    completion?(.failure(error))
                }
            } else {
                let error = NSError(domain: "", code: 0, userInfo: [NSLocalizedDescriptionKey : "Data was not retrieved from request"]) as Error
                completion?(.failure(error))
            }
        }
    }

    task.resume()
}

这会有问题吗？

Answer 1

听起来您正在尝试将 JSON 解码为响应。那是你的错误。鉴于您定义的结构和您显示的 JSON，您的 JSON 显然是(或打算是)航类数组，也就是说，Array<Flight>.self .这就是您需要解码的内容。

您的 Response 结构实际上显然与 JSON 无关；您不能解码为响应，因为 JSON 不是带有键 "flights" 的字典.您可以手动创建一个 Response 并设置它的 flights 手动到那个结果，但是你的 Response 结构，虽然它可能在存储方面派上用场，但与你的 JSON 无关。