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Code for Roll your own networking in Swift blog article: http://sundeepgupta.ca/post/161796783473/roll-your-own-swift-networking-code
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| import Foundation | |
| // MARK: - Public | |
| public struct WebService { | |
| let actionManager: ActionManager | |
| // As public API, optimize for simplicity by only providing a Result and not throwing. | |
| func getProfile(id: String, completion: @escaping (Result<Profile>) -> Void) { | |
| let action = Action<NSNull, Profile>(urlString: "api.com/profile", method: "GET", body: NSNull()) | |
| perform(action, completion: completion) | |
| } | |
| func createProfile(_ profile: Profile, completion: @escaping (Result<NSNull>) -> Void) { | |
| let action = Action<Profile, NSNull>(urlString: "api.com/profile", method: "POST", body: profile) | |
| perform(action, completion: completion) | |
| } | |
| private func perform<Req, Res>(_ action: Action<Req, Res>, completion: @escaping (Result<Res>) -> Void) { | |
| do { try actionManager.perform(action) { completion($0) } } | |
| catch { completion(Result.failure(error)) } | |
| } | |
| } | |
| public protocol Encodable { | |
| func encode() throws -> Data | |
| } | |
| public protocol Decodable { | |
| static func decode(data: Data) throws -> Self | |
| } | |
| public struct Profile: Encodable, Decodable { | |
| let name: String | |
| let age: Int | |
| public static func decode(data: Data) throws -> Profile { | |
| guard | |
| let object = try JSONSerialization.jsonObject(with: data) as? [String: Any], | |
| let name = object["name"] as? String, | |
| let age = object["age"] as? Int | |
| else { throw WebServiceError.invalidJSON(data) } | |
| return self.init(name: name, age: age) | |
| } | |
| public func encode() throws -> Data { | |
| let object: [String: Any] = ["name": name, "age": age] | |
| return try JSONSerialization.data(withJSONObject: object) | |
| } | |
| } | |
| extension NSNull: Encodable, Decodable { | |
| public static func decode(data: Data) throws -> Self { | |
| return self.init() | |
| } | |
| public func encode() throws -> Data { | |
| return Data() | |
| } | |
| } | |
| public enum Result<Value> { | |
| case success(Value) | |
| case failure(Error) | |
| } | |
| public enum WebServiceError: Error { | |
| case invalidURL(String) | |
| case invalidStatusCode(Int) | |
| case invalidJSON(Data) | |
| } | |
| // MARK: - Internal | |
| internal struct Action<RequestBody: Encodable, ResponseBody: Decodable> { | |
| let urlString: String | |
| let method: String | |
| let body: RequestBody | |
| let decode = ResponseBody.decode | |
| // Anything else you may need like tokens, headers, etc. | |
| func request() throws -> URLRequest { | |
| guard let url = URL(string: urlString) else { throw WebServiceError.invalidURL(urlString) } | |
| var request = URLRequest(url: url) | |
| request.httpMethod = method | |
| request.httpBody = try body.encode() | |
| return request | |
| } | |
| } | |
| internal struct ActionManager { | |
| let httpManager: HTTPManager | |
| func perform<Req, Res>(_ action: Action<Req, Res>, completion: @escaping (Result<Res>) -> Void) throws { | |
| let request = try action.request() | |
| httpManager.perform(request) { result in | |
| switch result { | |
| case .success(let data): | |
| do { completion(Result.success(try action.decode(data))) } | |
| catch { completion(Result.failure(error)) } | |
| case .failure(let error): completion(Result.failure(error)) | |
| } | |
| } | |
| } | |
| } | |
| internal struct HTTPManager { | |
| let urlSession: URLSession | |
| func perform(_ request: URLRequest, completion: @escaping (Result<Data>) -> Void) { | |
| urlSession.dataTask(with: request) { data, response, error in | |
| if error != nil { return completion(Result.failure(error!)) } | |
| let response = response as! HTTPURLResponse // Trusting the docs for this example! | |
| // Could pass in an object that deals with status codes, which would be part of the Action. | |
| guard response.statusCode == 200 else { | |
| return completion(Result.failure(WebServiceError.invalidStatusCode(response.statusCode))) | |
| } | |
| completion(Result.success(data ?? Data())) | |
| }.resume() | |
| } | |
| } |
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