Add a view with instructions for enabling backups in Element Classic. (#5359)

No presentation logic yet.

ElementX/Sources/Other/TestablePreview/TestablePreviewsDictionary.swift

@@ -18,6 +18,7 @@ enum TestablePreviewsDictionary {
         "AppLockSetupSettingsScreen_Previews" : AppLockSetupSettingsScreen_Previews.self,
         "AudioMediaEventsTimelineView_Previews" : AudioMediaEventsTimelineView_Previews.self,
         "AudioRoomTimelineView_Previews" : AudioRoomTimelineView_Previews.self,
+        "AuthenticationClassicAppBackupInstructionsView_Previews" : AuthenticationClassicAppBackupInstructionsView_Previews.self,
         "AuthenticationStartScreen_Previews" : AuthenticationStartScreen_Previews.self,
         "AvatarHeaderView_Previews" : AvatarHeaderView_Previews.self,
         "BadgeLabel_Previews" : BadgeLabel_Previews.self,

ElementX/Sources/Screens/Authentication/StartScreen/AuthenticationStartScreenModels.swift

@@ -55,6 +55,7 @@ struct AuthenticationStartScreenViewState: BindableState {
 
 struct AuthenticationStartScreenViewStateBindings {
     var alertInfo: AlertInfo<AuthenticationStartScreenAlertType>?
+    var showClassicAppBackupInstructions = false
 }
 
 enum AuthenticationStartScreenAlertType {

ElementX/Sources/Screens/Authentication/StartScreen/View/AuthenticationClassicAppBackupInstructionsView.swift

@@ -0,0 +1,74 @@
+//
+// Copyright 2026 Element Creations Ltd.
+//
+// SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+// Please see LICENSE files in the repository root for full details.
+//
+
+import Compound
+import SwiftUI
+
+struct AuthenticationClassicAppBackupInstructionsView: View {
+    let context: AuthenticationStartScreenViewModel.Context
+    
+    @Environment(\.dismiss) private var dismiss
+    
+    var body: some View {
+        ElementNavigationStack {
+            FullscreenDialog(topPadding: 24, horizontalPadding: 24) {
+                content
+            } bottomContent: {
+                buttons
+            }
+            .navigationBarTitleDisplayMode(.inline)
+            .toolbar { toolbar }
+            .background()
+            .backgroundStyle(.compound.bgSubtleSecondary)
+        }
+    }
+    
+    var content: some View {
+        VStack(alignment: .leading, spacing: 40) {
+            TitleAndIcon(title: L10n.screenMissingKeyBackupTitle(InfoPlistReader.main.bundleDisplayName),
+                         icon: \.keySolid,
+                         iconStyle: .default)
+            
+            SFNumberedListView(items: [
+                AttributedString(L10n.screenMissingKeyBackupStep1),
+                AttributedString(L10n.screenMissingKeyBackupStep2Ios),
+                AttributedString(L10n.screenMissingKeyBackupStep3Ios),
+                AttributedString(L10n.screenMissingKeyBackupStep4),
+                AttributedString(L10n.screenMissingKeyBackupStep5(InfoPlistReader.main.bundleDisplayName))
+            ])
+        }
+    }
+    
+    var buttons: some View {
+        Button(L10n.screenMissingKeyBackupOpenElementClassic) {
+            UIApplication.shared.open("element://open")
+        }
+        .buttonStyle(.compound(.primary))
+    }
+    
+    var toolbar: some ToolbarContent {
+        ToolbarItem(placement: .primaryAction) {
+            ToolbarButton(role: .close, action: dismiss.callAsFunction)
+        }
+    }
+}
+
+struct AuthenticationClassicAppBackupInstructionsView_Previews: PreviewProvider, TestablePreview {
+    static let viewModel = makeViewModel()
+    
+    static var previews: some View {
+        AuthenticationClassicAppBackupInstructionsView(context: viewModel.context)
+    }
+    
+    static func makeViewModel() -> AuthenticationStartScreenViewModel {
+        AuthenticationStartScreenViewModel(authenticationService: AuthenticationService.mock,
+                                           provisioningParameters: nil,
+                                           isBugReportServiceEnabled: false,
+                                           appSettings: ServiceLocator.shared.settings,
+                                           userIndicatorController: UserIndicatorControllerMock())
+    }
+}

ElementX/Sources/Screens/Authentication/StartScreen/View/AuthenticationStartScreen.swift

@@ -46,6 +46,9 @@ struct AuthenticationStartScreen: View {
             AuthenticationStartScreenBackgroundImage()
         }
         .alert(item: $context.alertInfo)
+        .sheet(isPresented: $context.showClassicAppBackupInstructions) {
+            AuthenticationClassicAppBackupInstructionsView(context: context)
+        }
         .introspect(.window, on: .supportedVersions) { window in
             context.send(viewAction: .updateWindow(window))
         }