Swift Concurrencyを利用したMVVMについて考える

Chiba.swift #1で発表したスライドです。
https://chibaswift.connpass.com/event/328367

Transcript

1. Swi$ ConcurrencyΛར༻ͨ͠ MVVMʹ͍ͭͯߟ͑Δ Chiba.swi) #1
2. ࣗݾ঺հ • coffmarkͱ͍͍·͢ɻ • υϫϯΰͰಇ͍͍ͯ·͢ɻ • 22৽ଔͰ͢ɻ • ઍ༿ݝʹॅΜͰ͍·͢ɻ
3. ؀ڥ • Xcode 15.4 • Swi/ 5.10 • ίϯύΠϥϑϥά • -strict-concurrency=targeted
4. ໨࣍ • RxSwi'Λར༻ͨ͠MVVM • Swi' ConcurrencyΛར༻ͨ͠MVVM • ํ਑ • ࣮૷಺༰ (APIݺͼग़͠΍ViewModelͷϝιουݺͼग़͠) • Preview • ·ͱΊ
5. RxSwi&Λར༻ͨ͠MVVMͷશମ૾
6. Swi$ ConcurrencyΛ ར༻ͨ͠MVVM
7. ํ਑ • task(priority:_:)Λ࢖͍ɺΩϟϯηϧॲཧΛࣗલ࣮૷͢Δ͜ͱ͕গ ͳ͍ܗͰಋೖΛਐΊ͍ͨͱߟ͍͑ͯ·͢ɻ • View͕ඇදࣔʹͳͬͨλΠϛϯάͰඇಉظॲཧ͕Ωϟϯηϧ ͞ΕΔ͔ΒͰ͢ɻ
8. Swi$ ConcurrencyΛར༻ͨ͠MVVMͷશମ૾
9. Viewͷॳظ࣮૷ struct ChibaView: View { /// Viewͷঢ়ଶ enum ViewState { /// ಡΈࠐΈத case loading /// ಡΈࠐΈ੒ޭ࣌ /// - response: Ϩεϙϯε /// - isLoading: ϩʔσΟϯάΠϯδέʔλͷදࣔ༗ແ case success(response: Response, isLoading: Bool) /// ಡΈࠐΈࣦഊ࣌ /// - isLoading: ϩʔσΟϯάΠϯδέʔλͷදࣔ༗ແ case error(isLoading: Bool) } var body: some View { ... } }
10. ViewModelͷॳظ࣮૷ @MainActor final class ChibaViewModel: ObservableObject { /// ViewState @Published private(set) var viewState: ChibaView.ViewState = .loading /// ΤϥʔΞϥʔτදࣔϑϥά @Published var isPresentAlert: Bool = false private let repository: RepositoryProtocol init(repository: RepositoryProtocol) { ... } }
11. APIݺͼग़͠ extension ChibaViewModel { // Actorִ཭͞Εͳ͍ nonisolated func resolveResponse() async throws -> Response { // (Repositoryʹ࣮૷) func resolve() -> Single<Response> try await repository.resolve().value } }
12. Swi$ ConcurrencyΛར༻ͨ͠MVVMͷશମ૾ (࠶ܝ)
13. View͔ΒViewModelͷϝιουݺͼग़͠ ଞʹ΋͋Δͱࢥ͍·͕͢ɺࠓճ͸ҎԼͷ3ͭΛߟ͑·͢ɻ 1. ॳճಡΈࠐΈ 2. Pull to Refresh 3. ΤϥʔΞϥʔτͷϦτϥΠ
14. ॳճಡΈࠐΈ (View࣮૷) struct ChibaView: View { @StateObject viewModel: ChibaViewModel // ը໘͕ॳճදࣔͨ͠λΠϛϯάͰॳճಡΈࠐΈΛ࣮ߦ͢ΔͨΊͷϑϥά @State private var viewDidLoad: Bool = false var body: some View { Group { switch viewModel.viewState { ... } } .task { if !viewDidLoad { viewDidLoad.toggle() await viewModel.initialLoad() } } } }
15. ॳճಡΈࠐΈ (ViewModel࣮૷) final class ChibaViewModel: ObservableObject { /// ॳճಡΈࠐΈΛ࣮ߦ func initialLoad() async { do { let response = try await resolveResponse() // ੒ޭ࣌ͷը໘Λදࣔ self.viewState = .success(response: response, isLoading: false) } catch { // Τϥʔը໘Λදࣔ self.viewState = .error(isLoading: false) } } }
16. Pull to Refresh (View࣮૷) struct ChibaView: View { // ... var body: some View { switch viewModel.viewState { case .success: successView(...) } } func successView(...) -> some View { ScrollView { ... } .refreshable { await viewModel.refresh() } } }
17. Pull to Refresh (ViewModel࣮૷) final class ChibaViewModel: ObservableObject { @Published var isPresentAlert: Bool = false func refresh() async { do { let response = try await resolveResponse() // ੒ޭ࣌ͷը໘Λදࣔ self.viewState = .success(response: response, isLoading: false) } catch { // ΤϥʔΞϥʔτΛදࣔ isPresentAlert = true } } }
18. ΤϥʔΞϥʔτͷϦτϥΠ (View࣮૷) struct ChibaView: View { var body: some View { Group { switch viewState { ... } } .alert("Error", isPresented: $viewModel.isPresentAlert) { Button("Cancel", role: .cancel) { } /// task(priority:_:)Ͱඇಉظؔ਺Λ࣮ߦ͢ΔϘλϯ AsyncButton { await viewModel.retry() } label: { Text("Retry") } } } }
19. AsyncBu(on.swi- /// ඇಉظؔ਺Λ࣮ߦ͢ΔϘλϯ struct AsyncButton<Label>: View where Label: View { @State private var isExecuting = false let action: () async -> Void let label: () -> Label public var body: some View { Button { if isExecuting { return } isExecuting.toggle() } label: { label() } .task(id: isExecuting) { guard isExecuting else { return } await action() isExecuting.toggle() } } }
20. ΤϥʔΞϥʔτͷϦτϥΠ (ViewModel࣮૷) final class ChibaViewModel: ObservableObject { func retry() async { // ϩʔσΟϯάදࣔ͢ΔͨΊviewStateͷisLoadingΛtrueʹมߋ transitionToLoading() do { let cards = try await resolveResponse() self.viewState = .success(cards: cards, isLoading: false) } catch { // ϩʔσΟϯάΛඇදࣔ͢ΔͨΊviewStateͷisLoadingΛfalseʹมߋ transitionToLoaded() isPresentAlert = true } } }
21. Preview #Preview { // MockoloΛར༻ let repository = RepositoryProtocolMock() repository.resolve = { @Sendable in .just(Response(...)) } return ChibaView( viewModel: ChibaViewModel( repository: repository ) ) }
22. ·ͱΊ • task(priority:_:)Λར༻ͯ͠ΩϟϯηϧॲཧΛࣗલ࣮૷͢Δ͜ͱ͕ গͳ͍ܗͰSwi1 ConcurrencyಋೖΛਐΊ͍ͯ͘͜ͱ͕Ͱ͖·͠ ͨɻ • طଘ࣮૷ΑΓϩʔΧϧม਺͸େ෯ʹগͳ͘ͳΔܗͰViewModel Λ࣮૷͢Δ͜ͱ͕Ͱ͖·ͨ͠ɻ
23. ࠓޙ • ը໘ભҠपΓ΋Swi%UIʹد͍͖͍ͤͯͨͱߟ͍͑ͯ·͢ɻ
24. ࢀߟ • Swi%UI ͷ Bu+on ͳͲͰτϦΨʔ͢Δ async ͳϝιουͷ࣮ߦ ΛɺΩϟϯηϧͷ͜ͱ·Ͱߟ࣮͑ͯ૷͢Δํ๏ 2બ • treastrain / Tanaka Ryoga͞Μ • h+ps:/ /zenn.dev/treastrain/arBcles/3effccd39f4056
25. ͝ਗ਼ௌ͋Γ͕ͱ͏͍͟͝·ͨ͠ɻ