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Lifecycle case study (#222)
* lifecycle * wip * wip * wip * wip * Xcode 11.3 compat * move * Update Examples/CaseStudies/SwiftUICaseStudies/04-HigherOrderReducers-Lifecycle.swift Co-authored-by: Stephen Celis <[email protected]> * tests * iOS 14 fix See: https://gist.github.com/stephencelis/3ac40c2aba73c45f76b35a0cce0864fd Co-authored-by: Stephen Celis <[email protected]>
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‎Examples/CaseStudies/CaseStudies.xcodeproj/project.pbxproj

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CA410EE2247C73B400E41798 /* 02-Effects-WebSocketTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = CA410EE1247C73B400E41798 /* 02-Effects-WebSocketTests.swift */; };
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CA3E4C5A24B4FA0E00447C0B /* 04-HigherOrderReducers-Lifecycle.swift */,
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DCE63B70245CC0B90080A23D /* 04-HigherOrderReducers-Recursion.swift */,
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DCC68EE22447C8540037F998 /* 04-HigherOrderReducers-ReusableFavoriting.swift */,
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CA0C0C4624B89BEC00CBDD8A /* 04-HigherOrderReducers-LifecycleTests.swift */,
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path = SwiftUICaseStudiesTests;
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sourceTree = "<group>";
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DC89C41B24460F95006900B9 /* 00-RootView.swift in Sources */,
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CA0C0C4724B89BEC00CBDD8A /* 04-HigherOrderReducers-LifecycleTests.swift in Sources */,
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CA50BE6024A8F46500FE7DBA /* 01-GettingStarted-AlertsAndActionSheetsTests.swift in Sources */,
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‎Examples/CaseStudies/SwiftUICaseStudies/00-Core.swift

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@@ -13,6 +13,7 @@ struct RootState {
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var effectsCancellation = EffectsCancellationState()
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var effectsTimers = TimersState()
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var episodes = EpisodesState(episodes: .mocks)
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var lifecycle = LifecycleDemoState()
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var loadThenNavigate = LoadThenNavigateState()
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var loadThenNavigateList = LoadThenNavigateListState()
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var loadThenPresent = LoadThenPresentState()
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case effectsBasics(EffectsBasicsAction)
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case effectsCancellation(EffectsCancellationAction)
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case episodes(EpisodesAction)
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case lifecycle(LifecycleDemoAction)
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case loadThenNavigate(LoadThenNavigateAction)
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case loadThenNavigateList(LoadThenNavigateListAction)
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case loadThenPresent(LoadThenPresentAction)
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action: /RootAction.episodes,
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environment: { .init(favorite: $0.favorite, mainQueue: $0.mainQueue) }
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),
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lifecycleDemoReducer
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.pullback(
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state: \.lifecycle,
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action: /RootAction.lifecycle,
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environment: { .init(mainQueue: $0.mainQueue )}
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),
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loadThenNavigateReducer
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.pullback(
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state: \.loadThenNavigate,

‎Examples/CaseStudies/SwiftUICaseStudies/00-RootView.swift

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)
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)
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NavigationLink(
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"Lifecycle",
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destination: LifecycleDemoView(
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store: self.store.scope(
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state: { $0.lifecycle },
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action: RootAction.lifecycle
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)
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)
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)
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NavigationLink(
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"Strict reducers",
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destination: DieRollView(

‎Examples/CaseStudies/SwiftUICaseStudies/04-HigherOrderReducers-Lifecycle.swift

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import ComposableArchitecture
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import ReactiveSwift
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import SwiftUI
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private let readMe = """
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This demonstrates how to trigger effects when a view appears, and cancel effects when a view \
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disappears. This can be helpful for starting up a feature's long living effects, such as timers, \
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location managers, etc. when that feature is first presented.
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To accomplish this we define a higher-order reducer that enhances any reducer with two additional \
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actions, `.onAppear` and `.onDisappear`, and a way to automate running effects when those actions \
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are sent to the store.
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"""
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extension Reducer {
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public func lifecycle(
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onAppear: @escaping (Environment) -> Effect<Action, Never>,
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onDisappear: @escaping (Environment) -> Effect<Never, Never>
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) -> Reducer<State?, LifecycleAction<Action>, Environment> {
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return .init { state, lifecycleAction, environment in
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switch lifecycleAction {
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case .onAppear:
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return onAppear(environment).map(LifecycleAction.action)
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case .onDisappear:
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return onDisappear(environment).fireAndForget()
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case let .action(action):
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guard state != nil else { return .none }
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return self.run(&state!, action, environment)
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.map(LifecycleAction.action)
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}
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}
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}
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}
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public enum LifecycleAction<Action> {
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case onAppear
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case onDisappear
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case action(Action)
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}
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extension LifecycleAction: Equatable where Action: Equatable {}
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struct LifecycleDemoState: Equatable {
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var count: Int?
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}
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enum LifecycleDemoAction: Equatable {
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case timer(LifecycleAction<TimerAction>)
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case toggleTimerButtonTapped
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}
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struct LifecycleDemoEnvironment {
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var mainQueue: DateScheduler
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}
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let lifecycleDemoReducer: Reducer<LifecycleDemoState, LifecycleDemoAction, LifecycleDemoEnvironment>
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= .combine(
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timerReducer.pullback(
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state: \.count,
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action: /LifecycleDemoAction.timer,
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environment: { TimerEnvironment(mainQueue: $0.mainQueue) }
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),
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Reducer { state, action, environment in
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switch action {
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case .timer:
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return .none
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case .toggleTimerButtonTapped:
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state.count = state.count == nil ? 0 : nil
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return .none
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}
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}
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)
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struct LifecycleDemoView: View {
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let store: Store<LifecycleDemoState, LifecycleDemoAction>
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var body: some View {
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WithViewStore(self.store) { viewStore in
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VStack {
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Button("Toggle Timer") { viewStore.send(.toggleTimerButtonTapped) }
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IfLetStore(
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self.store.scope(state: { $0.count }, action: LifecycleDemoAction.timer),
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then: TimerView.init(store:)
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)
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Spacer()
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}
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.navigationBarTitle("Lifecycle")
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}
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}
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}
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private struct TimerId: Hashable {}
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enum TimerAction {
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case decrementButtonTapped
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case incrementButtonTapped
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case tick
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}
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struct TimerEnvironment {
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var mainQueue: DateScheduler
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}
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private let timerReducer = Reducer<Int, TimerAction, TimerEnvironment> { state, action, TimerEnvironment in
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switch action {
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case .decrementButtonTapped:
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state -= 1
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return .none
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case .incrementButtonTapped:
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state += 1
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return .none
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case .tick:
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state += 1
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return .none
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}
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}
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.lifecycle(
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onAppear: {
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Effect.timer(id: TimerId(), every: .seconds(1), tolerance: .seconds(0), on: $0.mainQueue)
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.map { _ in TimerAction.tick }
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},
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onDisappear: { _ in
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.cancel(id: TimerId())
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})
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private struct TimerView: View {
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let store: Store<Int, LifecycleAction<TimerAction>>
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var body: some View {
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WithViewStore(self.store) { viewStore in
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Section {
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Text("Count: \(viewStore.state)")
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.onAppear { viewStore.send(.onAppear) }
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.onDisappear { viewStore.send(.onDisappear) }
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Button("Decrement") { viewStore.send(.action(.decrementButtonTapped))}
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Button("Increment") { viewStore.send(.action(.incrementButtonTapped)) }
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}
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}
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}
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}
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struct Lifecycle_Previews: PreviewProvider {
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static var previews: some View {
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Group {
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NavigationView {
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LifecycleDemoView(
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store: .init(
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initialState: .init(),
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reducer: lifecycleDemoReducer,
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environment: .init(
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mainQueue: QueueScheduler.main
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)
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)
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)
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}
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}
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}
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}

‎Examples/CaseStudies/SwiftUICaseStudiesTests/04-HigherOrderReducers-LifecycleTests.swift

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import Combine
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import ComposableArchitecture
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import ReactiveSwift
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import XCTest
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@testable import SwiftUICaseStudies
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8+
class LifecycleTests: XCTestCase {
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func testLifecycle() {
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let scheduler = TestScheduler()
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let store = TestStore(
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initialState: .init(),
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reducer: lifecycleDemoReducer,
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environment: .init(
16+
mainQueue: scheduler
17+
)
18+
)
19+
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store.assert(
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.send(.toggleTimerButtonTapped) {
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$0.count = 0
23+
},
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.send(.timer(.onAppear)),
26+
27+
.do { scheduler.advance(by: .seconds(1)) },
28+
.receive(.timer(.action(.tick))) {
29+
$0.count = 1
30+
},
31+
32+
.do { scheduler.advance(by: .seconds(1)) },
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.receive(.timer(.action(.tick))) {
34+
$0.count = 2
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},
36+
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.send(.timer(.action(.incrementButtonTapped))) {
38+
$0.count = 3
39+
},
40+
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.send(.timer(.action(.decrementButtonTapped))) {
42+
$0.count = 2
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},
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.send(.toggleTimerButtonTapped) {
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$0.count = nil
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},
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.send(.timer(.onDisappear))
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)
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}
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}

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