Rolling your own Network Stack

using the power of URLSession, Codable, protocols, and generics in Swift

Transcript

1. Rolling your own Network Stack using the power of URLSession, Codable, protocols, and generics in Swift Glenna Buford @glennersboofy
2. Hi, I'm glenna 2 Rolling your own network stack by @glennersboofy
3. Hi, I'm glenna 3 Rolling your own network stack by @glennersboofy
4. Hi, I'm glenna 4 Rolling your own network stack by @glennersboofy
5. Agenda • But why? • Brief showing of my naïve approach • Introduce: • Well, this would spoil it all :P 5 Rolling your own network stack by @glennersboofy
6. Motivation 6 Rolling your own network stack by @glennersboofy
7. Motivation 1 1 https:/ /blog.krzyzanowskim.com/2017/05/10/selling-t-shirt-selling-mobile-apps/ 7 Rolling your own network stack by @glennersboofy
8. 8 Rolling your own network stack by @glennersboofy
9. 9 Rolling your own network stack by @glennersboofy
10. 10 Rolling your own network stack by @glennersboofy
11. 11 Rolling your own network stack by @glennersboofy
12. 12 Rolling your own network stack by @glennersboofy
13. Agenda • But why? • Brief showing of my naïve approach 13 Rolling your own network stack by @glennersboofy
14. Setup 14 Rolling your own network stack by @glennersboofy
15. Setup 15 Rolling your own network stack by @glennersboofy
16. Setup let bookListsURL: String = "https://api.nytimes.com/svc/books/v3/lists/names?api-key=\(APIKeys.nyt)" let url: URL = URL(string: bookListsURL)! var urlRequest: URLRequest = URLRequest(url: url) urlRequest.httpMethod = HTTPMethod.get.rawValue 16 Rolling your own network stack by @glennersboofy
17. 17 Rolling your own network stack by @glennersboofy
18. URLSession 18 Rolling your own network stack by @glennersboofy
19. Setup let dataTask = URLSession.shared.dataTask(with: urlRequest) { (data, response, error) in guard error == nil else { //Handle error //Show user something return } guard let data: Data = data else { return } //do stuff with the new data } dataTask.resume() 19 Rolling your own network stack by @glennersboofy
20. let bookListsURL: String = "https://api.nytimes.com/svc/books/v3/lists/names?api-key=\(APIKeys.nyt)" let url: URL = URL(string: bookListsURL)! var urlRequest: URLRequest = URLRequest(url: url) urlRequest.httpMethod = HTTPMethod.get.rawValue let dataTask = URLSession.shared.dataTask(with: urlRequest) { (data, response, error) in guard error == nil else { //Handle error //Show user something return } guard let data: Data = data else { return } //do stuff with the new data } dataTask.resume() 20 Rolling your own network stack by @glennersboofy
21. 21 Rolling your own network stack by @glennersboofy
22. Agenda • But why? • Brief showing of my naïve approach • Introduce: 22 Rolling your own network stack by @glennersboofy
23. Agenda • But why? • Brief showing of my naïve approach • Introduce: • APIRouter 23 Rolling your own network stack by @glennersboofy
24. APIRouter protocol APIRouter { var urlRequest: URLRequest { get } } 24 Rolling your own network stack by @glennersboofy
25. enum NYTAPIRouter: APIRouter { case bestSellerCategories var urlRequest: URLRequest { let urlString: String = "\(host)\(route)?api-key=\(APIKeys.nyt)" let url: URL = URL(string: urlString)! var urlRequest: URLRequest = URLRequest(url: url) urlRequest.httpMethod = httpMethod.rawValue urlRequest.httpBody = body urlRequest.addValue("application/json", forHTTPHeaderField: "Accept") return urlRequest } ... } 25 Rolling your own network stack by @glennersboofy
26. enum NYTAPIRouter: APIRouter { ... private var route: String { switch self { case .bestSellerCategories: return "lists/names" } } private var httpMethod: HTTPMethod { switch self { case .bestSellerCategories: return .get } } ... } 26 Rolling your own network stack by @glennersboofy
27. 27 Rolling your own network stack by @glennersboofy
28. enum NYTAPIRouter: APIRouter { case bestSellerCategories case bestSellersOverview(Date?) ... } 28 Rolling your own network stack by @glennersboofy
29. let urlRequest: URLRequest = NYTAPIRouter.bestSellerCategories.urlRequest let dataTask = URLSession.shared.dataTask(with: urlRequest) { (data, response, error) in guard error == nil else { // Handle error return } guard let data: Data = data else { return } // Do some stuff with that data } dataTask.resume() 29 Rolling your own network stack by @glennersboofy
30. 30 Rolling your own network stack by @glennersboofy
31. ...but still 31 Rolling your own network stack by @glennersboofy
32. Agenda • But why? • Brief showing of my naïve approach • Introduce: • APIRouter 32 Rolling your own network stack by @glennersboofy
33. Agenda • But why? • Brief showing of my naïve approach • Introduce: • APIRouter • Rudimentary NetworkService and NetworkOperation 33 Rolling your own network stack by @glennersboofy
34. NetworkService struct NetworkService { static let shared: NetworkService = NetworkService() let operationQueue: OperationQueue = OperationQueue() func add(_ operation: Operation & NetworkOperationProtocol) { operation.operationState = .ready operationQueue.addOperation(operation) } } 34 Rolling your own network stack by @glennersboofy
35. 35 Rolling your own network stack by @glennersboofy
36. class NetworkOperation: Operation, NetworkOperationProtocol { private let request: URLRequest private let completion: ((Result<Data?, Error>) -> Void)? init(with apiRouter: APIRouter, completion: ((Result<Data?, Error>) -> Void)? = nil) { self.request = apiRouter.urlRequest self.completion = completion operationState = .none } private func performRequest() { ... } // MARK: Operation overrides ... // MARK: NetworkOperationProtocol ... } 36 Rolling your own network stack by @glennersboofy
37. private func performRequest() { let task = URLSession.shared.dataTask(with: request) { [weak self] (data, response, error) in guard let self = self else { return } if let error: Error = error { self.completion?(Result.failure(error)) } else { self.completion?(Result.success(data)) } } task.resume() } 37 Rolling your own network stack by @glennersboofy
38. ⚠ protocol NetworkOperationProtocol: class { var operationState: OperationState { get set } } enum OperationState: String { case none case ready = "isReady" case executing = "isExecuting" case finished = "isFinished" } 38 Rolling your own network stack by @glennersboofy
39. let bestSellersCategories: NYTAPIRouter = NYTAPIRouter.bestSellerCategories let op: NetworkOperation = NetworkOperation(with: bestSellersCategories) { result in switch result { case .success(let data): if let data: Data = data { // Do some stuff with that data } case .failure(let error): // oh no. } } NetworkService.shared.add(op) 39 Rolling your own network stack by @glennersboofy
40. Better, right? 40 Rolling your own network stack by @glennersboofy
41. 41 Rolling your own network stack by @glennersboofy
42. Agenda • But why? • Brief showing of my naïve approach • Introduce: • APIRouter • Rudimentary NetworkService and NetworkOperation 42 Rolling your own network stack by @glennersboofy
43. Agenda • But why? • Brief showing of my naïve approach • Introduce: • APIRouter • Rudimentary NetworkService and NetworkOperation • Generic-ify everything! 43 Rolling your own network stack by @glennersboofy
44. Or at least NetworkOperation 44 Rolling your own network stack by @glennersboofy
45. class NetworkOperation<T>: Operation, NetworkOperationProtocol where T: Decodable { ... private let completion: ((Result<T?, Error>) -> Void)? ... private func performRequest() { ... } } 45 Rolling your own network stack by @glennersboofy
46. private func performRequest() { let task = URLSession.shared.dataTask(with: request) { [weak self] (data, response, error) in guard let self = self else { return } if let error: Error = error { self.completion?(Result.failure(error)) } else { guard let data: Data = data else { self.completion?(Result.success(nil)) return } do { let decoded: T = try JSONDecoder().decode(T.self, from: data) self.completion?(Result.success(decoded)) } catch { self.completion?(Result.failure(error)) } } } task.resume() }
47. let bestSellersCategories: NYTAPIRouter = NYTAPIRouter.bestSellerCategories let op = NetworkOperation<[BestSellersCategory]>(with: bestSellerCategories) { result in switch result { case .success(let bestSellerList): // Woo! we have some usable data now case .failure(let error): // wah wah } } NetworkService.shared.add(op) 47 Rolling your own network stack by @glennersboofy
48. 48 Rolling your own network stack by @glennersboofy
49. Agenda • But why? • Brief showing of my naïve approach • Introduce: • APIRouter • Rudimentary NetworkService and NetworkOperation • Generic-ify everything! 49 Rolling your own network stack by @glennersboofy
50. 50 Rolling your own network stack by @glennersboofy
51. Levelling up • request adapter • retrier • use a custom URLSession in your NetworkService • add custom decode options • multiple APIRouters 51 Rolling your own network stack by @glennersboofy
52. Questions 52 Rolling your own network stack by @glennersboofy
53. Hi, I'm glenna @glennersboofy github.com/glenna github.com/glenna/NetworkStackExample 53 Rolling your own network stack by @glennersboofy