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generics - 如何使用 Codable 解析通用响应

问题描述

每个 API 在响应中都有三个参数。

  1. Code: 指示 API 是成功还是失败（1 或 0）
  2. Message: 一个字符串
  3. Data: 可以是Array对象或单个对象。

我已经创建了基本模型。

struct ResponseBase<T:Codable> : Codable {

    let code : String?
    let data : [T]
    let message : String?

    enum CodingKeys: String, CodingKey {
        case code = "Code"
        case data = "Data"
        case message = "Message"
    }

    init(from decoder: Decoder) throws {
        let values = try decoder.container(keyedBy: CodingKeys.self)
        code = try values.decodeIfPresent(String.self, forKey: .code)
        data = try values.decodeIfPresent([T].self, forKey: .data)
        message = try values.decodeIfPresent(String.self, forKey: .message)
    }
}

struct SocialWarmer : Codable {

    let createdDate : String?
    let lookUpId : String?
    let lookupKey : String?
    let lookupValue : String?
    let parentId : String?
    let statusFlag : String?
    let type : String?
    let updatedDate : String?

    enum CodingKeys: String, CodingKey {
        case createdDate = "CreatedDate"
        case lookUpId = "LookUpId"
        case lookupKey = "LookupKey"
        case lookupValue = "LookupValue"
        case parentId = "ParentId"
        case statusFlag = "StatusFlag"
        case type = "Type"
        case updatedDate = "UpdatedDate"
    }

    init(from decoder: Decoder) throws {
        let values = try decoder.container(keyedBy: CodingKeys.self)
        createdDate = try values.decodeIfPresent(String.self, forKey: .createdDate)
        lookUpId = try values.decodeIfPresent(String.self, forKey: .lookUpId)
        lookupKey = try values.decodeIfPresent(String.self, forKey: .lookupKey)
        lookupValue = try values.decodeIfPresent(String.self, forKey: .lookupValue)
        parentId = try values.decodeIfPresent(String.self, forKey: .parentId)
        statusFlag = try values.decodeIfPresent(String.self, forKey: .statusFlag)
        type = try values.decodeIfPresent(String.self, forKey: .type)
        updatedDate = try values.decodeIfPresent(String.self, forKey: .updatedDate)
    }

}

以下是 API 请求的代码。

class BaseApiClient {

    static let `default`  = BaseApiClient()

    private init() {

    }

    func fetch<model:Codable>(request:APIRouter,decoder : JSONDecoder = JSONDecoder()  ,onSuccess: @escaping ([model]) -> Void) {

        if Connectivity.isReachable {
            (UIApplication.shared.delegate as! AppDelegate).addProgressView()
            Alamofire.request(request).responseJSON { (response) in
                switch response.result {
                case .success( let apiResponse) :
                    DispatchQueue.main.async {
                        (UIApplication.shared.delegate as! AppDelegate).hideProgrssVoew()
                    }
                    if let responseData = apiResponse as? [String:Any] , let status  = responseData["Code"] as? String , status == "SUCCESS" {
                        do {
                            let responseModel  = try decoder.decode(ResponseBase<model>.self, from: response.data!)
                            onSuccess(responseModel.data!)
                        }
                        catch let error as NSError {
                            print("failed reason : \(error.localizedDescription)")
                        }

                        print(model.Type.self)
                        print(model.self)




                    }
                    else {
                        UIApplication.shared.gettopMostViewController()?.presentAlerterror(title: "Erorr", message: "Service not Avilabel" ,okclick: nil)
                    }
                case .failure(let error) :
                    UIApplication.shared.gettopMostViewController()?.presentAlerterror(title: "Erorr", message: error.localizedDescription, okclick: nil)
                }
            }
        }
        else {
            (UIApplication.shared.delegate as! AppDelegate).hideProgrssVoew()
            UIApplication.shared.gettopMostViewController()?.presentAlerterror(title: "Error", message: "connnection not avilabel", okclick: nil)
        }
    }

}

以下是调用 API 的代码。

BaseApiClient.default.fetch(request: APIRouter.GetSocialWarmerType) { (response: [SocialWarmer]) in
    print(response)
}

但是，如果数据是单个对象，则此模型和 API 方法将不起作用。我想要实现的是在 API 方法中创建单个模型和适当的更改，以解析对象数组和单个对象。

标签： genericscodable

解决方案

最后我找到了一个解决方法。我创建了两个基类，一个用于对象数组，一个用于单个对象。

struct ResponseBaseArray<T:Codable> : Codable {

    let code : String?
    let data : [T]?
    let message : String?

    enum CodingKeys: String, CodingKey {
        case code = "Code"
        case data = "Data"
        case message = "Message"
    }

    init(from decoder: Decoder) throws {
        let values = try decoder.container(keyedBy: CodingKeys.self)
        code = try values.decodeIfPresent(String.self, forKey: .code)
        data = try values.decodeIfPresent([T].self, forKey: .data)
        message = try values.decodeIfPresent(String.self, forKey: .message)
    }
}


struct ResponseBaseObject<T:Codable> : Codable {

    let code : String?
    let data : T?
    let message : String?

    enum CodingKeys: String, CodingKey {
        case code = "Code"
        case data = "Data"
        case message = "Message"
    }

    init(from decoder: Decoder) throws {
        let values = try decoder.container(keyedBy: CodingKeys.self)
        code = try values.decodeIfPresent(String.self, forKey: .code)
        data = try values.decodeIfPresent(T.self, forKey: .data)
        message = try values.decodeIfPresent(String.self, forKey: .message)
    }
}

以下是 Api 方法的代码。

class BaseApiClient {

    static let `default`  = BaseApiClient()

    private init() {

    }

    func fetch<model:Codable>(request:APIRouter , decoder: JSONDecoder = JSONDecoder() ,onSuccess: @escaping (model) -> Void) {

        if Connectivity.isReachable {
            (UIApplication.shared.delegate as! AppDelegate).addProgressView()
            Alamofire.request(request).responseJSON { (response) in
                switch response.result {
                case .success( let apiResponse) :

                    DispatchQueue.main.async {
                        (UIApplication.shared.delegate as! AppDelegate).hideProgrssVoew()
                    }
                    if let responseData = apiResponse as? [String:Any] , let status  = responseData["Code"] as? String , status == "SUCCESS" {
                        do {
                            let responseModel  = try decoder.decode(model.self, from: response.data!)
                            onSuccess(responseModel)
                        }
                        catch let error as NSError {
                            print("failed reason : \(error.localizedDescription)")
                        }
                    }
                    else {
                        UIApplication.shared.gettopMostViewController()?.presentAlerterror(title: "Erorr", message: "Service not Avilabel" ,okclick: nil)
                    }
                case .failure(let error) :
                    UIApplication.shared.gettopMostViewController()?.presentAlerterror(title: "Erorr", message: error.localizedDescription, okclick: nil)
                }
            }
        }
        else {
            (UIApplication.shared.delegate as! AppDelegate).hideProgrssVoew()
            UIApplication.shared.gettopMostViewController()?.presentAlerterror(title: "Error", message: "connnection not avilabel", okclick: nil)
        }
    }

}

以下是调用 API 的代码。

BaseApiClient.default.fetch(request: APIRouter.GetSocialWarmerType) { (rsult:ResponseBaseArray<[SocialWarmer]>) in
            print(rsult.data)
        }

如果您的 Api 返回单个对象而不是使用 ResponseBaseObject。

BaseApiClient.default.fetch(request: APIRouter.GetSocialWarmerType) { (rsult:ResponseBaseObject<SocialWarmer>) in
            print(rsult.data)
        }

但是只有当您已经知道您的 Api 将返回单个对象或对象数组时，此解决方案仍然有效。

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