Convert Network from Result+Completion to Async+Await

SWDestinyTrades/Classes/AddCard/Controller/AddCardViewController.swift

@@ -54,18 +54,7 @@ final class AddCardViewController: UIViewController {
     override func viewDidLoad() {
         super.viewDidLoad()
 
-        addCardView.startLoading()
-        destinyService.retrieveAllCards { [weak self] result in
-            self?.addCardView.stopLoading()
-            switch result {
-            case let .success(allCards):
-                self?.addCardView.updateSearchList(allCards)
-                self?.cards = allCards
-            case let .failure(error):
-                ToastMessages.showNetworkErrorMessage()
-                LoggerManager.shared.log(event: .allCards, parameters: ["error": error.localizedDescription])
-            }
-        }
+        fetchAllCards()
 
         addCardView.didSelectCard = { [weak self] card in
             self?.insert(card: card)
@@ -87,6 +76,26 @@ final class AddCardViewController: UIViewController {
 
     // MARK: - Helpers
 
+    private func fetchAllCards() {
+        addCardView.startLoading()
+        Task { [weak self] in
+            guard let self else { return }
+
+            defer {
+                self.addCardView.stopLoading()
+            }
+
+            do {
+                let allCards = try await self.destinyService.retrieveAllCards()
+                self.addCardView.updateSearchList(allCards)
+                self.cards = allCards
+            } catch {
+                ToastMessages.showNetworkErrorMessage()
+                LoggerManager.shared.log(event: .allCards, parameters: ["error": error.localizedDescription])
+            }
+        }
+    }
+
     private func insert(card: CardDTO) {
         switch addCardType {
         case .lent:

SWDestinyTrades/Classes/AddToDeck/Controller/AddToDeckViewController.swift

@@ -67,14 +67,22 @@ final class AddToDeckViewController: UIViewController {
 
     private func retrieveAllCards() {
         addToDeckView.activityIndicator.startAnimating()
-        destinyService.retrieveAllCards { [weak self] result in
-            self?.addToDeckView.activityIndicator.stopAnimating()
-            switch result {
-            case let .success(allCards):
-                self?.addToDeckView.addToDeckTableView.updateSearchList(allCards)
-                self?.cards = allCards
-            case let .failure(error):
-                self?.handleFailure(error)
+        Task { [weak self] in
+            guard let self else { return }
+
+            defer {
+                self.addToDeckView.activityIndicator.stopAnimating()
+            }
+
+            do {
+                let allCards = try await self.destinyService.retrieveAllCards()
+                self.addToDeckView.addToDeckTableView.updateSearchList(allCards)
+                self.cards = allCards
+            } catch APIError.requestCancelled {
+                // do nothing
+            } catch {
+                ToastMessages.showNetworkErrorMessage()
+                LoggerManager.shared.log(event: .allCards, parameters: ["error": error.localizedDescription])
             }
         }
     }
@@ -115,16 +123,6 @@ final class AddToDeckViewController: UIViewController {
         LoadingHUD.show(.labeledSuccess(title: L10n.added, subtitle: card.name))
     }
 
-    private func handleFailure(_ error: APIError) {
-        switch error {
-        case .requestCancelled:
-            break
-        default:
-            ToastMessages.showNetworkErrorMessage()
-            LoggerManager.shared.log(event: .allCards, parameters: ["error": error.localizedDescription])
-        }
-    }
-
     // MARK: - Navigation
 
     func navigateToNextController(with card: CardDTO) {

SWDestinyTrades/Classes/CardList/Controller/CardListViewController.swift

@@ -36,17 +36,8 @@ final class CardListViewController: UIViewController {
     override func viewDidLoad() {
         super.viewDidLoad()
 
-        cardListView.activityIndicator.startAnimating()
-        destinyService.retrieveSetCardList(setCode: setDTO.code.lowercased()) { [weak self] result in
-            self?.cardListView.activityIndicator.stopAnimating()
-            switch result {
-            case let .success(cardList):
-                self?.cardListView.cardListTableView.updateCardList(cardList)
-            case let .failure(error):
-                ToastMessages.showNetworkErrorMessage()
-                LoggerManager.shared.log(event: .cardsList, parameters: ["error": error.localizedDescription])
-            }
-        }
+        fetchSetCardList()
+
         cardListView.cardListTableView.didSelectCard = { [weak self] list, card in
             self?.navigateToNextController(cardList: list, card: card)
         }
@@ -58,6 +49,25 @@ final class CardListViewController: UIViewController {
         navigationItem.title = setDTO.name
     }
 
+    private func fetchSetCardList() {
+        cardListView.activityIndicator.startAnimating()
+        Task { [weak self] in
+            guard let self else { return }
+
+            defer {
+                self.cardListView.activityIndicator.stopAnimating()
+            }
+
+            do {
+                let cardList = try await self.destinyService.retrieveSetCardList(setCode: self.setDTO.code.lowercased())
+                self.cardListView.cardListTableView.updateCardList(cardList)
+            } catch {
+                ToastMessages.showNetworkErrorMessage()
+                LoggerManager.shared.log(event: .cardsList, parameters: ["error": error.localizedDescription])
+            }
+        }
+    }
+
     // MARK: - Navigation
 
     func navigateToNextController(cardList: [CardDTO], card: CardDTO) {

SWDestinyTrades/Classes/Rest/Base/APIError.swift

@@ -10,11 +10,15 @@ import Foundation
 
 enum APIError: Error {
     case requestFailed(reason: String?)
-    case jsonConversionFailure
+    case jsonConversionFailure(domain: String, description: String)
     case invalidData
     case responseUnsuccessful
     case jsonParsingFailure
     case requestCancelled
+    case keyNotFound(key: CodingKey, context: String)
+    case valueNotFound(type: Any.Type, context: String)
+    case typeMismatch(type: Any.Type, context: String)
+    case dataCorrupted(context: String)
 
     var localizedDescription: String {
         switch self {
@@ -26,10 +30,18 @@ enum APIError: Error {
             return "Response Unsuccessful"
         case .jsonParsingFailure:
             return "JSON Parsing Failure"
-        case .jsonConversionFailure:
-            return "JSON Conversion Failure"
+        case let .jsonConversionFailure(domain, description):
+            return "Error in read(from:ofType:) domain= \(domain), description= \(description)"
         case .requestCancelled:
             return "Request Cancelled"
+        case let .keyNotFound(key, context):
+            return "Could not find key \(key) in JSON: \(context)"
+        case let .valueNotFound(type, context):
+            return "Could not find type \(type) in JSON: \(context)"
+        case let .typeMismatch(type, context):
+            return "Type mismatch for type \(type) in JSON: \(context)"
+        case let .dataCorrupted(context):
+            return "Data found to be corrupted in JSON: \(context)"
         }
     }
 }

SWDestinyTrades/Classes/Rest/Base/HttpClient.swift

@@ -17,67 +17,38 @@ final class HttpClient: HttpClientProtocol {
 }
 
 extension HttpClient {
+
     var logger: NetworkingLogger {
         return NetworkingLogger(level: .debug)
     }
 
-    typealias DecodingCompletionHandler = (Decodable?, APIError?) -> Void
+    func request<T: Decodable>(_ request: URLRequest, decode: T.Type) async throws -> T {
+
+        logger.log(request: request)
 
-    private func decodingTask<T: Decodable>(with request: URLRequest,
-                                            decodingType: T.Type,
-                                            completionHandler completion: @escaping (T?, RequestError?) -> Void) -> URLSessionDataTask
-    {
         let requestDate = Date()
-        let task = session.dataTask(with: request) { [weak self] data, response, error in
+
+        do {
+            let (data, response) = try await session.data(for: request)
 
             let responseTime = Date().timeIntervalSince(requestDate)
 
             guard let httpResponse = response as? HTTPURLResponse else {
-                completion(nil, self?.failureReason(HttpStatusCode.unknown, error))
-                return
-            }
-            let statusCode = HttpStatusCode(fromRawValue: httpResponse.statusCode)
-            switch statusCode {
-            case .ok ... .permanentRedirect:
-                if let data = data {
-                    do {
-                        let model = try JSONDecoder().decode(decodingType, from: data)
-                        self?.logger.log(response: response, data: data, time: responseTime)
-                        completion(model, nil)
-                    } catch {
-                        completion(nil, RequestError(statusCode, reason: .jsonConversionFailure))
-                    }
-                } else {
-                    completion(nil, RequestError(statusCode, reason: .invalidData))
-                }
-            default:
-                completion(nil, RequestError(statusCode, reason: .responseUnsuccessful))
+                throw APIError.invalidData
             }
-        }
-        return task
-    }
 
-    func request<T: Decodable>(_ request: URLRequest, decode: ((T) -> T)?, completion: @escaping (Result<T, APIError>) -> Void) {
-        logger.log(request: request)
+            logger.log(response: response, data: data, time: responseTime)
 
-        let task = decodingTask(with: request, decodingType: T.self) { [weak self] json, error in
-
-            DispatchQueue.main.async {
-                if let error = error {
-                    self?.logger.logError(request: request, statusCode: error.statusCode.rawValue, error: error.reason)
-                    completion(.failure(error.reason))
-                    return
-                }
-                if let json = json {
-                    if let value = decode?(json) {
-                        completion(.success(value))
-                    } else {
-                        completion(.success(json))
-                    }
-                }
+            guard case 200 ... 300 = httpResponse.statusCode else {
+                throw APIError.responseUnsuccessful
             }
+
+            return try decodeData(data, decode: T.self)
+        } catch let error as URLError where error.code == .cancelled {
+            throw APIError.requestCancelled
+        } catch {
+            throw error
         }
-        task.resume()
     }
 
     func cancelAllRequests() {
@@ -90,12 +61,19 @@ extension HttpClient {
 
     // MARK: - Helper
 
-    private func failureReason(_ statusCode: HttpStatusCode, _ error: Error?) -> RequestError {
-        var reason: APIError = .requestFailed(reason: error?.localizedDescription)
-
-        if let error = error as NSError?, error.code == NSURLErrorCancelled {
-            reason = .requestCancelled
+    private func decodeData<T: Decodable>(_ data: Data, decode: T.Type) throws -> T {
+        do {
+            return try JSONDecoder().decode(T.self, from: data)
+        } catch let DecodingError.keyNotFound(key, context) {
+            throw APIError.keyNotFound(key: key, context: context.debugDescription)
+        } catch let DecodingError.valueNotFound(type, context) {
+            throw APIError.valueNotFound(type: type, context: context.debugDescription)
+        } catch let DecodingError.typeMismatch(type, context) {
+            throw APIError.typeMismatch(type: type, context: context.debugDescription)
+        } catch let DecodingError.dataCorrupted(context) {
+            throw APIError.dataCorrupted(context: context.debugDescription)
+        } catch let error as NSError {
+            throw APIError.jsonConversionFailure(domain: error.domain, description: error.localizedDescription)
         }
-        return RequestError(statusCode, reason: reason)
     }
 }

SWDestinyTrades/Classes/Rest/Base/HttpClientProtocol.swift

@@ -11,13 +11,14 @@ import Foundation
 protocol HttpClientProtocol {
     var logger: NetworkingLogger { get }
 
-    func request<T: Decodable>(_ request: URLRequest, decode: ((T) -> T)?, completion: @escaping (Result<T, APIError>) -> Void)
+    func request<T: Decodable>(_ request: URLRequest, decode: T.Type) async throws -> T
 
     func cancelAllRequests()
 }
 
 extension HttpClientProtocol {
-    func request<T: Decodable>(_ request: URLRequest, decode: ((T) -> T)? = nil, completion: @escaping (Result<T, APIError>) -> Void) {
-        self.request(request, decode: decode, completion: completion)
+
+    func request<T: Decodable>(_ request: URLRequest, decode: T.Type) async throws -> T {
+        try await self.request(request, decode: decode)
     }
 }

SWDestinyTrades/Classes/Rest/SWDestinyService.swift

@@ -9,45 +9,46 @@
 import Foundation
 
 final class SWDestinyService: SWDestinyServiceProtocol {
+
     private let client: HttpClientProtocol
 
     init(client: HttpClientProtocol = HttpClient()) {
         self.client = client
     }
 
-    func search(query: String, completion: @escaping (Result<[CardDTO], APIError>) -> Void) {
+    func search(query: String) async throws -> [CardDTO] {
         let endpoint: SWDestinyEndpoint = .search(query: query)
         let request = endpoint.request
 
-        client.request(request, completion: completion)
+        return try await client.request(request, decode: [CardDTO].self)
     }
 
-    func retrieveSetList(completion: @escaping (Result<[SetDTO], APIError>) -> Void) {
+    func retrieveSetList() async throws -> [SetDTO] {
         let endpoint: SWDestinyEndpoint = .setList
         let request = endpoint.request
 
-        client.request(request, completion: completion)
+        return try await client.request(request, decode: [SetDTO].self)
     }
 
-    func retrieveSetCardList(setCode: String, completion: @escaping (Result<[CardDTO], APIError>) -> Void) {
+    func retrieveSetCardList(setCode: String) async throws -> [CardDTO] {
         let endpoint: SWDestinyEndpoint = .cardList(setCode: setCode)
         let request = endpoint.request
 
-        client.request(request, completion: completion)
+        return try await client.request(request, decode: [CardDTO].self)
     }
 
-    func retrieveAllCards(completion: @escaping (Result<[CardDTO], APIError>) -> Void) {
+    func retrieveAllCards() async throws -> [CardDTO] {
         let endpoint: SWDestinyEndpoint = .allCards
         let request = endpoint.request
 
-        client.request(request, completion: completion)
+        return try await client.request(request, decode: [CardDTO].self)
     }
 
-    func retrieveCard(cardId: String, completion: @escaping (Result<CardDTO, APIError>) -> Void) {
+    func retrieveCard(cardId: String) async throws -> CardDTO {
         let endpoint: SWDestinyEndpoint = .card(cardId: cardId)
         let request = endpoint.request
 
-        client.request(request, completion: completion)
+        return try await client.request(request, decode: CardDTO.self)
     }
 
     func cancelAllRequests() {

SWDestinyTrades/Classes/Rest/SWDestinyServiceProtocol.swift

@@ -9,15 +9,16 @@
 import Foundation
 
 protocol SWDestinyServiceProtocol {
-    func search(query: String, completion: @escaping (Result<[CardDTO], APIError>) -> Void)
 
-    func retrieveSetList(completion: @escaping (Result<[SetDTO], APIError>) -> Void)
+    func search(query: String) async throws -> [CardDTO]
 
-    func retrieveSetCardList(setCode: String, completion: @escaping (Result<[CardDTO], APIError>) -> Void)
+    func retrieveSetList() async throws -> [SetDTO]
 
-    func retrieveAllCards(completion: @escaping (Result<[CardDTO], APIError>) -> Void)
+    func retrieveSetCardList(setCode: String) async throws -> [CardDTO]
 
-    func retrieveCard(cardId: String, completion: @escaping (Result<CardDTO, APIError>) -> Void)
+    func retrieveAllCards() async throws -> [CardDTO]
+
+    func retrieveCard(cardId: String) async throws -> CardDTO
 
     func cancelAllRequests()
 }