swift - 在 swift 4 中解码动态 JSON 结构

Question

我有以下问题，我不确定如何处理。

我的 JSON 响应可能如下所示:

{ 
  "data": {
      "id": 7,
      "token": "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJleHAiOjE1NDY1MTU0NDMsImRhdGEiOiJ2bGFkVGVzdCIsImlhdCI6MTU0NjUwODI0M30.uwuPhlnchgBG4E8IvHvK4bB1Yj-TNDgmi7wUAiKmoVo"
   },
  "error": null
}

或者像这样:

{
 "data": [{
     "id": 12
    }, {
      "id": 2
    }, {
       "id": 5
    }, {
       "id": 7
    }],
 "error": null
}

所以简而言之，数据可以是单个对象或数组。我所拥有的是:

struct ApiData: Decodable {
    var data: DataObject?
    var error: String?
}

struct DataObject: Decodable {
    var userId: Int?

    enum CodingKeys: String, CodingKey {
        case userId = "id"
    }
}

这对于第一个用例工作正常，但一旦数据变成

var 数据:[DataObject?]

如何在不重复代码的情况下实现动态化？

编辑:这也是我解码对象的方式

 func makeDataTaskWith(with urlRequest: URLRequest, completion: @escaping(_ apiData: ApiData?) -> ()) {
    let config = URLSessionConfiguration.default
    let session = URLSession(configuration: config)

    session.dataTask(with: urlRequest) {
        (data, response, error) in
        guard let _ = response, let data = data else {return}

        if let responseCode = response as? HTTPURLResponse {
            print("Response has status code: \(responseCode.statusCode)")
        }

        do {
            let retreived = try NetworkManager.shared.decoder.decode(ApiData.self, from: data)
            completion(retreived)
        } catch let decodeError as NSError {
            print("Decoder error: \(decodeError.localizedDescription)\n")
            return
        }
        }.resume()
}

Answer 1

如果 data 可以是单个对象或数组，则编写一个自定义初始化器，它首先解码一个数组，如果发生类型不匹配错误，则解码单个对象。 data 无论如何都声明为数组。

由于 token 仅出现在单个对象中，因此该属性被声明为可选。

struct ApiData: Decodable {
    let data : [DataObject]
    let error : String?

    private enum CodingKeys : String, CodingKey { case data, error }

    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        do {
            data = try container.decode([DataObject].self, forKey: .data)
        } catch DecodingError.typeMismatch {
            data = [try container.decode(DataObject.self, forKey: .data)]
        }
        error = try container.decodeIfPresent(String.self, forKey: .error)
    }
}


struct DataObject: Decodable {
    let userId : Int
    let token : String?

    private enum CodingKeys: String, CodingKey { case userId = "id", token }
}

编辑:可以改进您接收数据的代码。您应该添加更好的错误处理以返回所有可能的错误:

func makeDataTaskWith(with urlRequest: URLRequest, completion: @escaping(ApiData?, Error?) -> Void) {
    let config = URLSessionConfiguration.default
    let session = URLSession(configuration: config)

    session.dataTask(with: urlRequest) {
        (data, response, error) in
        if let error = error { completion(nil, error); return }

        if let responseCode = response as? HTTPURLResponse {
            print("Response has status code: \(responseCode.statusCode)")
        }

        do {
            let retreived = try NetworkManager.shared.decoder.decode(ApiData.self, from: data!)
            completion(retreived, nil)
        } catch {
            print("Decoder error: ", error)
            completion(nil, error)
        }
        }.resume()
}