在swift 3中生成您自己的错误代码

Question

我想要实现的是URLSession在swift 3中执行请求.我在一个单独的函数中执行此操作(以便不为GET和POST单独编写代码)并返回URLSessionDataTask并处理闭包中的成功和失败.有点像这样 -

let task = URLSession.shared.dataTask(with: request) { (data, uRLResponse, responseError) in

     DispatchQueue.main.async {

          var httpResponse = uRLResponse as! HTTPURLResponse

          if responseError != nil && httpResponse.statusCode == 200{

               successHandler(data!)

          }else{

               if(responseError == nil){
                     //Trying to achieve something like below 2 lines
                     //Following line throws an error soo its not possible
                     //var errorTemp = Error(domain:"", code:httpResponse.statusCode, userInfo:nil)

                     //failureHandler(errorTemp)

               }else{

                     failureHandler(responseError!)
               }
          }
     }
}

我不希望处理此函数中的错误条件,并希望使用响应代码生成错误,并返回此错误以在任何调用此函数的位置处理它.任何人都可以告诉我该怎么做？或者这不是处理这种情况的"快速"方式吗？

Answer 1

在您的情况下,错误是您正在尝试生成Error实例.Error在Swift 3中是一种可用于定义自定义错误的协议.此功能特别适用于在不同操作系统上运行的纯Swift应用程序.

在iOS开发中,NSError该类仍然可用,并且它符合Error协议.

因此,如果您的目的只是传播此错误代码,则可以轻松替换

var errorTemp = Error(domain:"", code:httpResponse.statusCode, userInfo:nil)

同

var errorTemp = NSError(domain:"", code:httpResponse.statusCode, userInfo:nil)

否则,请检查Sandeep Bhandari关于如何创建自定义错误类型的答案

Answer 2

您可以LocalizedError使用以下值创建符合Swift 协议的协议:

protocol OurErrorProtocol: LocalizedError {

    var title: String? { get }
    var code: Int { get }
}

这使我们能够创建具体的错误:

struct CustomError: OurErrorProtocol {

    var title: String?
    var code: Int
    var errorDescription: String? { return _description }
    var failureReason: String? { return _description }

    private var _description: String

    init(title: String?, description: String, code: Int) {
        self.title = title ?? "Error"
        self._description = description
        self.code = code
    }
}

Answer 3

你可以创建枚举来处理错误:)

enum RikhError: Error {
    case unknownError
    case connectionError
    case invalidCredentials
    case invalidRequest
    case notFound
    case invalidResponse
    case serverError
    case serverUnavailable
    case timeOut
    case unsuppotedURL
 }

然后在enum中创建一个方法来接收http响应代码并返回相应的错误:)

static func checkErrorCode(_ errorCode: Int) -> RikhError {
        switch errorCode {
        case 400:
            return .invalidRequest
        case 401:
            return .invalidCredentials
        case 404:
            return .notFound
        //bla bla bla
        default:
            return .unknownError
        }
    }

最后更新你的故障块以接受RikhError类型的单个参数:)

我有一个详细的教程,关于如何使用Swift3将传统的基于Objective-C的面向对象的网络模型重构为现代的面向协议的模型https://learnwithmehere.blogspot.in看看:)

希望能帮助到你 :)

Answer 4

您应该使用NSError对象.

let error = NSError(domain:"", code:401, userInfo:[ NSLocalizedDescriptionKey: "Invalid access token"])

然后将NSError转换为Error对象

Answer 5

实现LocalizedError:

struct StringError : LocalizedError
{
    var errorDescription: String? { return mMsg }
    var failureReason: String? { return mMsg }
    var recoverySuggestion: String? { return "" }
    var helpAnchor: String? { return "" }

    private var mMsg : String

    init(_ description: String)
    {
        mMsg = description
    }
}

请注意,简单地实现Error,例如,如其中一个答案中所述,将失败(至少在Swift 3中),并且调用localizedDescription将导致字符串"操作无法完成.(.Stringtring error 1) "

Answer 6

 let error = NSError(domain:"", code:401, userInfo:[ NSLocalizedDescriptionKey: "Invaild UserName or Password"]) as Error
            self.showLoginError(error)

创建一个 NSError 对象并将其类型转换为 Error ，在任何地方显示它

private func showLoginError(_ error: Error?) {
    if let errorObj = error {
        UIAlertController.alert("Login Error", message: errorObj.localizedDescription).action("OK").presentOn(self)
    }
}

Answer 7

我仍然认为哈利的答案是最简单和完整的，但如果您需要更简单的东西，请使用：

struct AppError {
    let message: String

    init(message: String) {
        self.message = message
    }
}

extension AppError: LocalizedError {
    var errorDescription: String? { return message }
//    var failureReason: String? { get }
//    var recoverySuggestion: String? { get }
//    var helpAnchor: String? { get }
}

并像这样使用或测试它：

printError(error: AppError(message: "My App Error!!!"))

func print(error: Error) {
    print("We have an ERROR: ", error.localizedDescription)
}

Answer 8

细节

• Xcode版本10.2.1（10E1001）
• 迅捷5

解决应用中的错误的解决方案

import Foundation

enum AppError {
    case network(type: Enums.NetworkError)
    case file(type: Enums.FileError)
    case custom(errorDescription: String?)

    class Enums { }
}

extension AppError: LocalizedError {
    var errorDescription: String? {
        switch self {
            case .network(let type): return type.localizedDescription
            case .file(let type): return type.localizedDescription
            case .custom(let errorDescription): return errorDescription
        }
    }
}

// MARK: - Network Errors

extension AppError.Enums {
    enum NetworkError {
        case parsing
        case notFound
        case custom(errorCode: Int?, errorDescription: String?)
    }
}

extension AppError.Enums.NetworkError: LocalizedError {
    var errorDescription: String? {
        switch self {
            case .parsing: return "Parsing error"
            case .notFound: return "URL Not Found"
            case .custom(_, let errorDescription): return errorDescription
        }
    }

    var errorCode: Int? {
        switch self {
            case .parsing: return nil
            case .notFound: return 404
            case .custom(let errorCode, _): return errorCode
        }
    }
}

// MARK: - FIle Errors

extension AppError.Enums {
    enum FileError {
        case read(path: String)
        case write(path: String, value: Any)
        case custom(errorDescription: String?)
    }
}

extension AppError.Enums.FileError: LocalizedError {
    var errorDescription: String? {
        switch self {
            case .read(let path): return "Could not read file from \"\(path)\""
            case .write(let path, let value): return "Could not write value \"\(value)\" file from \"\(path)\""
            case .custom(let errorDescription): return errorDescription
        }
    }
}

用法

//let err: Error = NSError(domain:"", code: 401, userInfo: [NSLocalizedDescriptionKey: "Invaild UserName or Password"])
let err: Error = AppError.network(type: .custom(errorCode: 400, errorDescription: "Bad request"))

switch err {
    case is AppError:
        switch err as! AppError {
        case .network(let type): print("Network ERROR: code \(type.errorCode), description: \(type.localizedDescription)")
        case .file(let type):
            switch type {
                case .read: print("FILE Reading ERROR")
                case .write: print("FILE Writing ERROR")
                case .custom: print("FILE ERROR")
            }
        case .custom: print("Custom ERROR")
    }
    default: print(err)
}

Answer 9

protocol CustomError : Error {

    var localizedTitle: String
    var localizedDescription: String

}

enum RequestError : Int, CustomError {

    case badRequest         = 400
    case loginFailed        = 401
    case userDisabled       = 403
    case notFound           = 404
    case methodNotAllowed   = 405
    case serverError        = 500
    case noConnection       = -1009
    case timeOutError       = -1001

}

func anything(errorCode: Int) -> CustomError? {

      return RequestError(rawValue: errorCode)
}