User session state machine crashes

ElementX/Sources/Screens/HomeScreen/HomeScreenCoordinator.swift

@@ -23,10 +23,10 @@ struct HomeScreenCoordinatorParameters {
 }
 
 enum HomeScreenCoordinatorAction {
-    case presentRoom(roomIdentifier: String)
-    case presentSettings
-    case presentBugReport
-    case verifySession
+    case presentRoomScreen(roomIdentifier: String)
+    case presentSettingsScreen
+    case presentFeedbackScreen
+    case presentSessionVerificationScreen
     case signOut
 }
 
@@ -63,11 +63,11 @@ final class HomeScreenCoordinator: Coordinator, Presentable {
 
             switch action {
             case .selectRoom(let roomIdentifier):
-                self.callback?(.presentRoom(roomIdentifier: roomIdentifier))
+                self.callback?(.presentRoomScreen(roomIdentifier: roomIdentifier))
             case .userMenu(let action):
                 self.processUserMenuAction(action)
             case .verifySession:
-                self.callback?(.verifySession)
+                self.callback?(.presentSessionVerificationScreen)
             }
         }
     }
@@ -87,11 +87,11 @@ final class HomeScreenCoordinator: Coordinator, Presentable {
     private func processUserMenuAction(_ action: HomeScreenViewUserMenuAction) {
         switch action {
         case .settings:
-            callback?(.presentSettings)
+            callback?(.presentSettingsScreen)
         case .inviteFriends:
             presentInviteFriends()
         case .feedback:
-            callback?(.presentBugReport)
+            callback?(.presentFeedbackScreen)
         case .signOut:
             callback?(.signOut)
         }

ElementX/Sources/UserSession/UserSessionFlowCoordinator.swift

@@ -72,6 +72,12 @@ class UserSessionFlowCoordinator: Coordinator {
                 self.presentSettingsScreen()
             case (.settingsScreen, .dismissedSettingsScreen, .homeScreen):
                 self.dismissSettingsScreen()
+
+            case (.homeScreen, .feedbackScreen, .feedbackScreen):
+                self.presentFeedbackScreen()
+            case (.feedbackScreen, .dismissedFeedbackScreen, .homeScreen):
+                self.dismissFeedbackScreen()
+
             case (_, .resignActive, .suspended):
                 self.pause()
             case (_, .becomeActive, _):
@@ -109,13 +115,13 @@ class UserSessionFlowCoordinator: Coordinator {
             guard let self else { return }
 
             switch action {
-            case .presentRoom(let roomIdentifier):
+            case .presentRoomScreen(let roomIdentifier):
                 self.stateMachine.processEvent(.showRoomScreen(roomId: roomIdentifier))
-            case .presentSettings:
+            case .presentSettingsScreen:
                 self.stateMachine.processEvent(.showSettingsScreen)
-            case .presentBugReport:
-                self.presentBugReportScreen()
-            case .verifySession:
+            case .presentFeedbackScreen:
+                self.stateMachine.processEvent(.feedbackScreen)
+            case .presentSessionVerificationScreen:
                 self.stateMachine.processEvent(.showSessionVerificationScreen)
             case .signOut:
                 self.callback?(.signOut)
@@ -254,42 +260,42 @@ class UserSessionFlowCoordinator: Coordinator {
 
         alert.addAction(UIAlertAction(title: ElementL10n.no, style: .cancel))
         alert.addAction(UIAlertAction(title: ElementL10n.yes, style: .default) { [weak self] _ in
-            self?.presentBugReportScreen()
+            self?.stateMachine.processEvent(.feedbackScreen)
         })
 
         navigationRouter.present(alert, animated: true)
     }
 
-    private func presentBugReportScreen(for image: UIImage? = nil) {
+    private func presentFeedbackScreen(for image: UIImage? = nil) {
         let parameters = BugReportCoordinatorParameters(bugReportService: bugReportService,
                                                         screenshot: image)
         let coordinator = BugReportCoordinator(parameters: parameters)
-        coordinator.completion = { [weak self, weak coordinator] in
-            guard let self, let coordinator = coordinator else { return }
-            self.navigationRouter.dismissModule(animated: true)
-            self.remove(childCoordinator: coordinator)
+        coordinator.completion = { [weak self] in
+            self?.stateMachine.processEvent(.dismissedFeedbackScreen)
         }
 
         add(childCoordinator: coordinator)
         coordinator.start()
         let navController = ElementNavigationController(rootViewController: coordinator.toPresentable())
         navController.navigationBar.topItem?.leftBarButtonItem = UIBarButtonItem(barButtonSystemItem: .cancel,
                                                                                  target: self,
-                                                                                 action: #selector(dismissBugReportScreen))
+                                                                                 action: #selector(handleFeedbackScreenCancellation))
         navController.isModalInPresentation = true
         navigationRouter.present(navController, animated: true)
     }
 
     @objc
-    private func dismissBugReportScreen() {
-        MXLog.debug("dismissBugReportScreen")
-
-        guard let bugReportCoordinator = childCoordinators.first(where: { $0 is BugReportCoordinator }) else {
+    private func handleFeedbackScreenCancellation() {
+        stateMachine.processEvent(.dismissedFeedbackScreen)
+    }
+
+    private func dismissFeedbackScreen() {
+        guard let coordinator = childCoordinators.first(where: { $0 is BugReportCoordinator }) else {
             return
         }
-
+        
         navigationRouter.dismissModule()
-        remove(childCoordinator: bugReportCoordinator)
+        remove(childCoordinator: coordinator)
     }
 
     // MARK: - Application State

ElementX/Sources/UserSession/UserSessionFlowCoordinatorStateMachine.swift

@@ -33,6 +33,9 @@ class UserSessionFlowCoordinatorStateMachine {
         /// Showing the session verification flows
         case sessionVerificationScreen
 
+        /// Showing the session verification flows
+        case feedbackScreen
+
         /// Showing the settings screen
         case settingsScreen
 
@@ -51,15 +54,20 @@ class UserSessionFlowCoordinatorStateMachine {
         /// The room screen has been dismissed
         case dismissedRoomScreen
 
-        /// Request the start of the session verification flow
-        case showSessionVerificationScreen
-        /// Session verification has finished
-        case dismissedSessionVerificationScreen
-
         /// Request presentation of the settings screen
         case showSettingsScreen
         /// The settings screen has been dismissed
         case dismissedSettingsScreen
+
+        /// Request presentation of the feedback screen
+        case feedbackScreen
+        /// The feedback screen has been dismissed
+        case dismissedFeedbackScreen
+
+        /// Request the start of the session verification flow
+        case showSessionVerificationScreen
+        /// Session verification has finished
+        case dismissedSessionVerificationScreen
 
         /// Application goes into inactive state
         case resignActive
@@ -68,13 +76,14 @@ class UserSessionFlowCoordinatorStateMachine {
     }
 
     private let stateMachine: StateMachine<State, Event>
-    private var stateBeforeSuspension: State = .initial
+    private var stateBeforeSuspension: State?
 
     init() {
         stateMachine = StateMachine(state: .initial)
         configure()
     }
 
+    // swiftlint:disable:next cyclomatic_complexity
     private func configure() {
         stateMachine.addRoutes(event: .start, transitions: [.initial => .homeScreen])
 
@@ -84,23 +93,46 @@ class UserSessionFlowCoordinatorStateMachine {
                 return .roomScreen(roomId: roomId)
             case (.dismissedRoomScreen, .roomScreen):
                 return .homeScreen
-            case (.resignActive, _):
-                self.stateBeforeSuspension = fromState
-                return .suspended
-            case (.becomeActive, .suspended):
-                return self.stateBeforeSuspension
+
             case (.showSettingsScreen, .homeScreen):
                 return .settingsScreen
             case (.dismissedSettingsScreen, .settingsScreen):
                 return .homeScreen
+
+            case (.feedbackScreen, .homeScreen):
+                return .feedbackScreen
+            case (.dismissedFeedbackScreen, .feedbackScreen):
+                return .homeScreen
+
             case (.showSessionVerificationScreen, .homeScreen):
                 return .sessionVerificationScreen
             case (.dismissedSessionVerificationScreen, .sessionVerificationScreen):
                 return .homeScreen
+
+            case (.resignActive, _):
+                self.stateBeforeSuspension = fromState
+                return .suspended
+            case (.becomeActive, _):
+                // Cannot become active if not previously suspended
+                // Happens when the app is backgrounded before the session is setup
+                guard let previousState = self.stateBeforeSuspension else {
+                    return self.stateMachine.state
+                }
+
+                return previousState
+
             default:
                 return nil
             }
         }
+
+        addTransitionHandler { context in
+            if let event = context.event {
+                MXLog.info("Transitioning from `\(context.fromState)` to `\(context.toState)` with event `\(event)`")
+            } else {
+                MXLog.info("Transitioning from \(context.fromState)` to `\(context.toState)`")
+            }
+        }
     }
 
     /// Attempt to move the state machine to another state through an event

changelog.d/277.bugfix

@@ -0,0 +1 @@
+Fix state machine crashes when backgrounding the app before the user session is setup