對於常用的 WebAPI 呼叫方式進行擴充 URLSession

Example.swift

/// 範例中使用了 SVProgressHUD, SwiftyJSON
/// 另外 UIAlertController 有 extension
func request(_ path: String, method: HttpMethod = .get, parameters: [String: Any]? = nil, localizedStatus: String? = NSLocalizedString("資料處理中", comment: "呼叫API讀取狀態文字"), _ completion: @escaping (_ json: JSON) -> Void) {
        
        // 顯示 ActivityIndicator
        if let status = localizedStatus { SVProgressHUD.show(withStatus: status) }
        
        // 待會使用 GCD 版本所以要 Dispatch 到其他 thread
        DispatchQueue.global().async {
            
            // 基本的 header
            var headers = ["Content-Type": "application/json"]
            
            // token
            if let token = UserDefaults.standard.string(forKey: udkAuthToken) {
                headers["Authorization"] = "JWT \(token)"
            }
            
            do {
                // 使用 URLSession extension 功能
                let data = try URLSession.ephemeral().request(self.baseUrl.appending(path), method: method, headers: headers, parameters: parameters)
                
                DispatchQueue.main.async {
                    // 完成
                    completion(JSON(data: data))
                }
            } catch let error as HttpError {
                // 處理 Http Errors
                switch error {
                case .unAuthorized:
                    // 實作驗證失效邏輯 -> 顯示登入畫面
                    NotificationCenter.default.post(name: .didAuthFailure, object: nil)
                    break
                default:
                    // 實作其他錯誤的對應邏輯 -> 顯示錯誤訊息 (每個狀態都有對應錯誤訊息)
                    NotificationCenter.default.post(name: .presentNotifyStatus, object: nil, userInfo: [kGUNotificationUserInfoMessageKey: error.localizedDescription, kGUNotificationUserInfoStatusKey: NotifyStatus.error])
                    break
                }
            } catch {
                // 非 Http Error 類
                UIAlertController(error: error).present()
            }
            
            DispatchQueue.main.async {
                // 隱藏 ActivityIndicator
                SVProgressHUD.dismiss()
            }
        }
        
//        let config = URLSessionConfiguration.ephemeral  
//        let session = URLSession(configuration: config)
//        
//        var req = URLRequest(url: URL(string: baseUrl.appending(path))!)
//        
//        req.httpMethod = method.rawValue
//        req.addValue("application/json", forHTTPHeaderField: "Content-Type")
//        
//        if let token = UserDefaults.standard.string(forKey: udkAuthToken) {
//            req.addValue("JWT \(token)", forHTTPHeaderField: "Authorization")
//        }
//        
//        if let parameters = parameters, let data = try? JSONSerialization.data(withJSONObject: parameters, options: [.prettyPrinted]) {
//            req.httpBody = data
//        }
//        
//        
//        
//        if let status = localizedStatus { SVProgressHUD.show(withStatus: status) }
//        session.dataTask(with: req) {(data, res, error) in
//            SVProgressHUD.dismiss()
//            
//            var json: JSON?
//            
//            if let data = data {
//                json = JSON(data: data)
//            }
//            
//            DispatchQueue.main.async {
//                if error != nil {
//                    let message = NSLocalizedString("發生錯誤 (0)", comment: "客戶端端發生錯誤")
//                    NotificationCenter.default.post(name: .presentNotifyStatus, object: nil, userInfo: [kGUNotificationUserInfoMessageKey: message, kGUNotificationUserInfoStatusKey: NotifyStatus.error])
//                    return completion(nil)
//                }
//
//                if let res = res as? HTTPURLResponse {
//                    if res.statusCode >= 400 {
//                        switch res.statusCode {
//                        case 400:
//                            if let json = json {
//                                let message = json["message"].stringValue
//                                NotificationCenter.default.post(name: .presentNotifyStatus, object: nil, userInfo: [
//                                    // 來自伺服器的訊息
//                                    kGUNotificationUserInfoMessageKey: NSLocalizedString(message, comment: ""),
//                                    kGUNotificationUserInfoStatusKey: NotifyStatus.error
//                                ])
//                                return completion(nil)
//                            } else {
//                                NotificationCenter.default.post(name: .presentNotifyStatus, object: nil, userInfo: [
//                                    kGUNotificationUserInfoMessageKey: NSLocalizedString("傳送資料格式錯誤", comment: "傳送資料格式錯誤"),
//                                    kGUNotificationUserInfoStatusKey: NotifyStatus.error
//                                ])
//                                return completion(nil)
//                            }
//                        case 401:
//                            NotificationCenter.default.post(name: .didAuthFailure, object: nil)
//                            return completion(nil)
//                        default:
//                            print(res.statusCode)
//                            NotificationCenter.default.post(name: .presentNotifyStatus, object: nil, userInfo: [
//                                kGUNotificationUserInfoMessageKey: NSLocalizedString("伺服器正在維修中", comment: "伺服器無法連線"),
//                                kGUNotificationUserInfoStatusKey: NotifyStatus.error
//                            ])
//                            return completion(nil)
//                        }
//                    }
//                }
//                
//                completion(json)
//            }
//        }.resume()
    }

URLSessionWebAPIExtension.swift

//
//  URLSessionExtension.swift
//
//  簡化 URLSession 使用時初始化的工作量
//
//  Created by 默司 on 2017/1/12.
//  Copyright © 2016年 默司. All rights reserved.
//
enum HttpMethod: String {
    case get = "GET"
    case post = "POST"
    case put = "PUT"
    case delete = "DELETE"
}

enum HttpError: Error {
    case badRequest(String)
    case unAuthorized
    case forbidden
    case notFound
    case internalServerError
    case badGateway
    case serviceUnavailable
    case userNetworking
    
    var localizedDescription: String {
        switch self {
        case .badRequest(let reason):
            return NSLocalizedString(reason, comment: "")
        case .unAuthorized:
            return NSLocalizedString("授權無效", comment: "")
        case .forbidden:
            return NSLocalizedString("禁止訪問", comment: "")
        case .notFound:
            return NSLocalizedString("服務端點不存在", comment: "")
        case .internalServerError:
            return NSLocalizedString("伺服器異常", comment: "")
        case .badGateway:
            return NSLocalizedString("伺服器閘道異常", comment: "")
        case .serviceUnavailable:
            return NSLocalizedString("無法連線到伺服器", comment: "")
        default:
            return NSLocalizedString("網路連線錯誤", comment: "")
        }
    }
}

extension URLSession {
    
    /// 建立新的 URLSession 實體，不使用快取
    ///
    /// - Returns:
    static func ephemeral() -> URLSession { return URLSession(configuration: URLSessionConfiguration.ephemeral) }
    
    /// 建立新的 URLSession 實體，使用快取
    ///
    /// - Returns:
    static func `default`() -> URLSession { return URLSession(configuration: URLSessionConfiguration.default) }
    
    /// 通用請求
    ///
    /// - Parameters:
    ///   - urlString: 網址
    ///   - method:
    ///   - headers:
    ///   - parameters: 參數
    ///   - completion:
    /// - Returns:
    @discardableResult func request(_ urlString: String, method: HttpMethod, headers: [String: String]? = nil, parameters: [String: Any]? = nil, _ completion: @escaping (_ data: Data?, _ res: HTTPURLResponse?, _ error: Error?) -> Void) -> URLSession {
        
        var req = URLRequest(url: URL(string: urlString)!)
        req.httpMethod = method.rawValue
        
        if let parameters = parameters, let data = try? JSONSerialization.data(withJSONObject: parameters, options: [.prettyPrinted]) {
            req.httpBody = data
        }
        
        if let headers = headers {
            Array(headers.keys).forEach({ (key) in
                req.setValue(headers[key], forHTTPHeaderField: key)
            })
        }
        
        self.dataTask(with: req) { completion($0, $1 as? HTTPURLResponse, $2) }.resume()
        
        return self
    }
    
    /// GET 請求
    ///
    /// - Parameters:
    ///   - urlString: 網址
    ///   - headers:
    ///   - completion:
    /// - Returns:
    @discardableResult func get(_ urlString: String, headers: [String : String]? = nil, _ completion: @escaping (_ data: Data?, _ res: HTTPURLResponse?, _ error: Error?) -> Void) -> URLSession {
        
        return self.request(urlString, method: .get, headers: headers, completion)
    }
    
    /// POST 請求
    ///
    /// - Parameters:
    ///   - urlString: 網址
    ///   - headers:
    ///   - parameters: 參數
    ///   - completion:
    /// - Returns:
    @discardableResult func post(_ urlString: String, headers: [String : String]? = nil, parameters: [String: Any]? = nil, _ completion: @escaping (_ data: Data?, _ res: HTTPURLResponse?, _ error: Error?) -> Void) -> URLSession {
        
        return self.request(urlString, method: .post, headers: headers, parameters: parameters, completion)
    }
    
    /// PUT 請求
    ///
    /// - Parameters:
    ///   - urlString: 網址
    ///   - headers:
    ///   - parameters: 參數
    ///   - completion:
    /// - Returns:
    @discardableResult func put(_ urlString: String, headers: [String : String]? = nil, parameters: [String: Any]? = nil, _ completion: @escaping (_ data: Data?, _ res: HTTPURLResponse?, _ error: Error?) -> Void) -> URLSession {
        
        return self.request(urlString, method: .put, headers: headers, parameters: parameters, completion)
    }
    
    /// DELETE 請求
    ///
    /// - Parameters:
    ///   - urlString: 網址
    ///   - headers:
    ///   - completion:
    /// - Returns:
    @discardableResult func delete(_ urlString: String, headers: [String : String]? = nil, _ completion: @escaping (_ data: Data?, _ res: HTTPURLResponse?, _ error: Error?) -> Void) -> URLSession {
        
        return self.request(urlString, method: .delete, headers: headers, completion)
    }
    
    /// 通用請求，GCD 同步版
    ///
    /// 目前支援JSON格式、String格式的錯誤訊息
    ///
    /// - Parameters:
    ///   - urlString: 網址
    ///   - headers:
    ///   - parameters: 參數
    ///   - completion:
    /// - Returns:
    /// - Throws: HTTP ERROR
    func request(_ urlString: String, method: HttpMethod, headers: [String: String]? = nil, parameters: [String: Any]? = nil) throws -> Data {
        let semaphore = DispatchSemaphore(value: 0)
        
        var statusCode: Int = 0
        var data: Data?
        var error: Error?
        
        self.request(urlString, method: method, headers: headers, parameters: parameters) { (d, r, e) in
            statusCode = r?.statusCode ?? 0
            data = d
            error = e
            
            semaphore.signal()
        }
        
        semaphore.wait()
        
        if let error = error { throw error }
        if statusCode >= 400 {
            switch statusCode {
            case 400:
                let unknown = NSLocalizedString("輸入參數錯誤", comment: "")
                
                guard let data = data else {
                    throw HttpError.badRequest(unknown)
                }
                
                // JSON 格式支援
                let json = (try? JSONSerialization.jsonObject(with: data, options: .mutableContainers)) as? [String: Any]
                var message = json?["message"] as? String
                
                if message == nil {
                    // 文字格式支援
                    message = String.init(data: data, encoding: .utf8)
                }
                
                let reason = NSLocalizedString(message ?? "輸入參數錯誤" , comment: "")
                
                throw HttpError.badRequest(reason)
            case 401:
                throw HttpError.unAuthorized
            case 403:
                throw HttpError.forbidden
            case 404:
                throw HttpError.notFound
            case 500:
                throw HttpError.internalServerError
            case 502:
                throw HttpError.badGateway
            case 503:
                throw HttpError.serviceUnavailable
            default:
                throw HttpError.userNetworking
            }
        }
        
        return data!
    }
    
    /// GET 請求，GCD 同步版
    ///
    /// - Parameters:
    ///   - urlString: 網址
    ///   - headers:
    /// - Returns:
    /// - Throws: HTTP ERROR
    func get(_ urlString: String, headers: [String : String]? = nil) throws -> Data {
        
        return try self.request(urlString, method: .get, headers: headers)
    }
    
    /// POST 請求，GCD 同步版
    ///
    /// - Parameters:
    ///   - urlString: 網址
    ///   - headers:
    ///   - parameters: 參數
    /// - Returns:
    /// - Throws: HTTP ERROR
    func post(_ urlString: String, headers: [String : String]? = nil, parameters: [String: Any]? = nil) throws -> Data {
        
        return try self.request(urlString, method: .post, headers: headers, parameters: parameters)
    }
    
    /// PUT 請求，GCD 同步版
    ///
    /// - Parameters:
    ///   - urlString: 網址
    ///   - headers:
    ///   - parameters: 參數
    /// - Returns:
    /// - Throws: HTTP ERROR
    func put(_ urlString: String, headers: [String : String]? = nil, parameters: [String: Any]? = nil) throws -> Data {
        
        return try self.request(urlString, method: .put, headers: headers, parameters: parameters)
    }
    
    /// DELETE 請求，GCD 同步版
    ///
    /// - Parameters:
    ///   - urlString: 網址
    ///   - headers:
    /// - Returns:
    /// - Throws: HTTP ERROR
    func delete(_ urlString: String, headers: [String : String]? = nil) throws -> Data {
        
        return try self.request(urlString, method: .delete, headers: headers)
    }
}