Add boot detection in the NSE and use this to inform the user that there may be more notifications. (#5054)

* Add an initial implementation of the receivedWhileOfflineNotification.

* Only deliver a single receivedWhileOffline notification per boot and clarify the API.

* Add a 15-minute threshold for the receiveWhileOfflineNotification.

ElementX.xcodeproj/project.pbxproj

@@ -184,6 +184,7 @@
 		1C4CB9009E50E6535883D5B2 /* RestorationToken.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3558A15CFB934F9229301527 /* RestorationToken.swift */; };
 		1C598D3B785645AAC7B35760 /* ReportRoomScreenCoordinator.swift in Sources */ = {isa = PBXBuildFile; fileRef = 292EEE1F71DCC205C45728F7 /* ReportRoomScreenCoordinator.swift */; };
 		1C6B06DB15EC194AF35C05DB /* RoomPowerLevelsProxy.swift in Sources */ = {isa = PBXBuildFile; fileRef = CFFA5E881D281810AB428EA3 /* RoomPowerLevelsProxy.swift */; };
+		1C6B2A1A5A9699DD4C9755B3 /* BootDetectionManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6F054DE7D47849687662C9D9 /* BootDetectionManager.swift */; };
 		1C8BC70A18060677E295A846 /* ShareToMapsAppActivity.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4481799F455B3DA243BDA2AC /* ShareToMapsAppActivity.swift */; };
 		1C9BB74711E5F24C77B7FED0 /* RoomMembersListScreenCoordinator.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5AEA0B743847CFA5B3C38EE4 /* RoomMembersListScreenCoordinator.swift */; };
 		1D5DC685CED904386C89B7DA /* NSRegularExpresion.swift in Sources */ = {isa = PBXBuildFile; fileRef = 95BAC0F6C9644336E9567EE6 /* NSRegularExpresion.swift */; };
@@ -716,13 +717,11 @@
 		7BDC3976D88D40D2A45BEB8C /* NSRegularExpresion.swift in Sources */ = {isa = PBXBuildFile; fileRef = 95BAC0F6C9644336E9567EE6 /* NSRegularExpresion.swift */; };
 		7BF368A78E6D9AFD222F25AF /* SecureBackupScreenViewModel.swift in Sources */ = {isa = PBXBuildFile; fileRef = 7AE094FCB6387D268C436161 /* SecureBackupScreenViewModel.swift */; };
 		7C0E29E0279866C62EC67A28 /* JoinRoomScreenViewModelTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = DE5127D6EA05B2E45D0A7D59 /* JoinRoomScreenViewModelTests.swift */; };
-		7C101936C8F3DAF8D8166124 /* DataProtectionManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = 75821CD31A4BD02B99C327A4 /* DataProtectionManager.swift */; };
 		7C164A642E8932B5F9004550 /* test_voice_message.m4a in Resources */ = {isa = PBXBuildFile; fileRef = DCA2D836BD10303F37FAAEED /* test_voice_message.m4a */; };
 		7C1A7B594B2F8143F0DD0005 /* ElementXAttributeScope.swift in Sources */ = {isa = PBXBuildFile; fileRef = C024C151639C4E1B91FCC68B /* ElementXAttributeScope.swift */; };
 		7C545FFEC9930F7247352593 /* SecurityAndPrivacyScreenViewModel.swift in Sources */ = {isa = PBXBuildFile; fileRef = 978092B01BEAB39F2C4389AE /* SecurityAndPrivacyScreenViewModel.swift */; };
 		7C6376192F578E0BA801BFEC /* AnalyticsSettingsScreenModels.swift in Sources */ = {isa = PBXBuildFile; fileRef = 42C64A14EE89928207E3B42B /* AnalyticsSettingsScreenModels.swift */; };
 		7C9BDF1FC7BD46C4676536AB /* AuthenticationStartScreenBackgroundImage.swift in Sources */ = {isa = PBXBuildFile; fileRef = 682BC7BAF0EFEF512A8C5140 /* AuthenticationStartScreenBackgroundImage.swift */; };
-		7CD05B18A432060E4770FBD8 /* DataProtectionManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = 75821CD31A4BD02B99C327A4 /* DataProtectionManager.swift */; };
 		7CD16990BA843BE9ED639129 /* ImageRoomTimelineItem.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3DFE4453AB0B34C203447162 /* ImageRoomTimelineItem.swift */; };
 		7D249465ED00988EEEC14E05 /* JoinedRoomProxyMock.swift in Sources */ = {isa = PBXBuildFile; fileRef = 867DC9530C42F7B5176BE465 /* JoinedRoomProxyMock.swift */; };
 		7D261B5119E78CC8E771CA15 /* GlobalSearchScreenCoordinator.swift in Sources */ = {isa = PBXBuildFile; fileRef = 74653BE903970C0E36867D46 /* GlobalSearchScreenCoordinator.swift */; };
@@ -988,6 +987,7 @@
 		A851635B3255C6DC07034A12 /* RoomScreenCoordinator.swift in Sources */ = {isa = PBXBuildFile; fileRef = B8108C8F0ACF6A7EB72D0117 /* RoomScreenCoordinator.swift */; };
 		A87DC550659C5176AC1829DE /* ElementTextFieldStyle.swift in Sources */ = {isa = PBXBuildFile; fileRef = D7673F2B0B038FAB2A8D16AD /* ElementTextFieldStyle.swift */; };
 		A88328D7E17F73AB64501B51 /* DSWaveformImageViews in Frameworks */ = {isa = PBXBuildFile; productRef = 2A4106A0A96DC4C273128AA5 /* DSWaveformImageViews */; };
+		A8E324E700E596E36B0A311B /* BootDetectionManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6F054DE7D47849687662C9D9 /* BootDetectionManager.swift */; };
 		A8FA7671948E3DF27F320026 /* BugReportFlowCoordinator.swift in Sources */ = {isa = PBXBuildFile; fileRef = 7367B3B9A8CAF902220F31D1 /* BugReportFlowCoordinator.swift */; };
 		A91D125414C3D9ABBABCF2F1 /* KZFileWatchers in Frameworks */ = {isa = PBXBuildFile; productRef = 6690850AA47ECED7E1CAB345 /* KZFileWatchers */; };
 		A93661C962B12942C08864B6 /* WysiwygComposer in Frameworks */ = {isa = PBXBuildFile; productRef = CA07D57389DACE18AEB6A5E2 /* WysiwygComposer */; };
@@ -2146,6 +2146,7 @@
 		6E5E9C044BEB7C70B1378E91 /* UserSession.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = UserSession.swift; sourceTree = "<group>"; };
 		6E964AF2DFEB31E2B799999F /* RoomPollsHistoryScreenModels.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RoomPollsHistoryScreenModels.swift; sourceTree = "<group>"; };
 		6EA1D2CBAEA5D0BD00B90D1B /* BindableState.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = BindableState.swift; sourceTree = "<group>"; };
+		6F054DE7D47849687662C9D9 /* BootDetectionManager.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = BootDetectionManager.swift; sourceTree = "<group>"; };
 		6F1C3CBBC62C566DDF5E84C1 /* TimelineItemMenuAction.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TimelineItemMenuAction.swift; sourceTree = "<group>"; };
 		6F3DFE5B444F131648066F05 /* StateStoreViewModel.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StateStoreViewModel.swift; sourceTree = "<group>"; };
 		6F65E4BB9E82EB8373207CF8 /* MediaProviderMock.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MediaProviderMock.swift; sourceTree = "<group>"; };
@@ -2189,7 +2190,6 @@
 		7509AB72755DCC4B4E721B36 /* sv */ = {isa = PBXFileReference; lastKnownFileType = text.plist.strings; name = sv; path = sv.lproj/SAS.strings; sourceTree = "<group>"; };
 		752A0EB49BF5BCEA37EDF7A3 /* Signposter.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Signposter.swift; sourceTree = "<group>"; };
 		753B4C6C0EDDCBF0708DC384 /* TimelineItemSendInfoLabel.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TimelineItemSendInfoLabel.swift; sourceTree = "<group>"; };
-		75821CD31A4BD02B99C327A4 /* DataProtectionManager.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DataProtectionManager.swift; sourceTree = "<group>"; };
 		75B3CE05643C7791D46AC54B /* LeaveSpaceHandleProxy.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LeaveSpaceHandleProxy.swift; sourceTree = "<group>"; };
 		76310030C831D4610A705603 /* URLComponentsTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = URLComponentsTests.swift; sourceTree = "<group>"; };
 		76A46ABD27628CB5FC402541 /* Backports.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Backports.swift; sourceTree = "<group>"; };
@@ -5207,7 +5207,7 @@
 		864330656491EBAADA4901D3 /* Sources */ = {
 			isa = PBXGroup;
 			children = (
-				75821CD31A4BD02B99C327A4 /* DataProtectionManager.swift */,
+				6F054DE7D47849687662C9D9 /* BootDetectionManager.swift */,
 				D7BB243B26D54EF1A0C422C0 /* NotificationContentBuilder.swift */,
 				BB6ED50FE104992419310EEB /* NotificationHandler.swift */,
 				27A1AD6389A4659AF0CEAE62 /* NotificationServiceExtension.swift */,
@@ -7532,12 +7532,12 @@
 				CDCA8A559E098503DDE29477 /* AttributedStringBuilder.swift in Sources */,
 				BA43D782BE85C7F5F20C624A /* AttributedStringBuilderProtocol.swift in Sources */,
 				F255083E18CDBFDF7E640FB1 /* Avatars.swift in Sources */,
+				A8E324E700E596E36B0A311B /* BootDetectionManager.swift in Sources */,
 				9A3B0CDF097E3838FB1B9595 /* Bundle.swift in Sources */,
 				9295F1F5E04484E10780BCE8 /* CharacterSet.swift in Sources */,
 				238D561CA231339C6D4D06F3 /* ClientBuilder.swift in Sources */,
 				0BAF83521871E69D222EE8E4 /* ClientBuilderHook.swift in Sources */,
 				211B5F524E851178EE549417 /* CurrentValuePublisher.swift in Sources */,
-				7CD05B18A432060E4770FBD8 /* DataProtectionManager.swift in Sources */,
 				24A75F72EEB7561B82D726FD /* Date.swift in Sources */,
 				FE9A5D4715C7AB68682C030C /* Dictionary.swift in Sources */,
 				9F11B9F347F9E2D236799FB3 /* ElementCallServiceConstants.swift in Sources */,
@@ -7945,6 +7945,7 @@
 				54FDA3625AACBD9E438D084D /* BlurEffectView.swift in Sources */,
 				B6DF6B6FA8734B70F9BF261E /* BlurHashDecode.swift in Sources */,
 				E794AB6ABE1FF5AF0573FEA1 /* BlurHashEncode.swift in Sources */,
+				1C6B2A1A5A9699DD4C9755B3 /* BootDetectionManager.swift in Sources */,
 				A8FA7671948E3DF27F320026 /* BugReportFlowCoordinator.swift in Sources */,
 				F4C005F006FC3657B9F0A31D /* BugReportHook.swift in Sources */,
 				6AD722DD92E465E56D2885AB /* BugReportScreen.swift in Sources */,
@@ -8017,7 +8018,6 @@
 				A722F426FD81FC67706BB1E0 /* CustomLayoutLabelStyle.swift in Sources */,
 				12C867E85E6D12EEDFD0B127 /* CustomStringConvertible.swift in Sources */,
 				9905C1B1C6EFE38F3A6533F3 /* Data.swift in Sources */,
-				7C101936C8F3DAF8D8166124 /* DataProtectionManager.swift in Sources */,
 				C6C06DDA8881260303FBA3A0 /* Date.swift in Sources */,
 				99C463F12F89C99C77D02077 /* DeactivateAccountScreen.swift in Sources */,
 				3E3CC3D17908A3BB9F224CC5 /* DeactivateAccountScreenCoordinator.swift in Sources */,

ElementX/Resources/Localizations/en-US.lproj/Localizable.strings

@@ -454,6 +454,7 @@
 "notification_mentioned_you_body" = "Mentioned you: %1$@";
 "notification_new_messages" = "New Messages";
 "notification_reaction_body" = "Reacted with %1$@";
+"notification_received_while_offline_ios" = "You received one or more notifications while offline.";
 "notification_room_invite_body" = "Invited you to join the room";
 "notification_room_invite_body_with_sender" = "%1$@ invited you to join the room";
 "notification_sender_me" = "Me";

ElementX/Resources/Localizations/en.lproj/Localizable.strings

@@ -454,6 +454,7 @@
 "notification_mentioned_you_body" = "Mentioned you: %1$@";
 "notification_new_messages" = "New Messages";
 "notification_reaction_body" = "Reacted with %1$@";
+"notification_received_while_offline_ios" = "You received one or more notifications while offline.";
 "notification_room_invite_body" = "Invited you to join the room";
 "notification_room_invite_body_with_sender" = "%1$@ invited you to join the room";
 "notification_sender_me" = "Me";

ElementX/Sources/Application/Settings/AppSettings.swift

@@ -14,7 +14,9 @@ import Foundation
 import SwiftUI
 
 /// Common settings between app and NSE
-protocol CommonSettingsProtocol {
+protocol CommonSettingsProtocol: AnyObject {
+    var lastNotificationBootTime: TimeInterval? { get set }
+    
     var logLevel: LogLevel { get }
     var traceLogPacks: Set<TraceLogPack> { get }
     var bugReportRageshakeURL: RemotePreference<RageshakeConfiguration> { get }
@@ -51,6 +53,7 @@ final class AppSettings {
         case enableNotifications
         case enableInAppNotifications
         case pusherProfileTag
+        case lastNotificationBootTime
         case logLevel
         case traceLogPacks
         case viewSourceEnabled
@@ -291,6 +294,10 @@ final class AppSettings {
     @UserPreference(key: UserDefaultsKeys.pusherProfileTag, storageType: .userDefaults(store))
     var pusherProfileTag: String?
     
+    /// The device's last boot time as recorded by the NSE.
+    @UserPreference(key: UserDefaultsKeys.lastNotificationBootTime, storageType: .userDefaults(store))
+    var lastNotificationBootTime: TimeInterval?
+    
     // MARK: - Logging
         
     @UserPreference(key: UserDefaultsKeys.logLevel, defaultValue: LogLevel.info, storageType: .userDefaults(store))

ElementX/Sources/Generated/Strings.swift

@@ -1060,6 +1060,8 @@ internal enum L10n {
   internal static func notificationReactionBody(_ p1: Any) -> String {
     return L10n.tr("Localizable", "notification_reaction_body", String(describing: p1))
   }
+  /// You received one or more notifications while offline.
+  internal static var notificationReceivedWhileOfflineIos: String { return L10n.tr("Localizable", "notification_received_while_offline_ios") }
   /// Mark as read
   internal static var notificationRoomActionMarkAsRead: String { return L10n.tr("Localizable", "notification_room_action_mark_as_read") }
   /// Quick reply

ElementX/Sources/Other/Extensions/UNNotificationContent.swift

@@ -29,6 +29,10 @@ extension UNNotificationContent {
     @objc var threadRootEventID: String? {
         userInfo[NotificationConstants.UserInfoKey.threadRootEventIdentifier] as? String
     }
+    
+    var unreadCount: Int? {
+        userInfo[NotificationConstants.UserInfoKey.unreadCount] as? Int
+    }
 }
 
 extension UNMutableNotificationContent {
@@ -40,7 +44,7 @@ extension UNMutableNotificationContent {
             userInfo[NotificationConstants.UserInfoKey.receiverIdentifier] = newValue
         }
     }
-
+    
     override var roomID: String? {
         get {
             userInfo[NotificationConstants.UserInfoKey.roomIdentifier] as? String
@@ -67,8 +71,4 @@ extension UNMutableNotificationContent {
             userInfo[NotificationConstants.UserInfoKey.threadRootEventIdentifier] = newValue
         }
     }
-    
-    var unreadCount: Int? {
-        userInfo[NotificationConstants.UserInfoKey.unreadCount] as? Int
-    }
 }

ElementX/Sources/Services/Notification/Manager/NotificationManager.swift

@@ -56,8 +56,14 @@ final class NotificationManager: NSObject, NotificationManagerProtocol {
                 self?.enableNotifications(newValue)
             }
             .store(in: &cancellables)
-    }
         
+        NotificationCenter.default.publisher(for: UIApplication.didBecomeActiveNotification)
+            .sink { [weak self] _ in
+                self?.removeReceivedWhileOfflineNotification()
+            }
+            .store(in: &cancellables)
+    }
+    
     func requestAuthorization() {
         guard appSettings.enableNotifications, !userSession.isNil else { return }
         Task {
@@ -151,6 +157,10 @@ final class NotificationManager: NSObject, NotificationManagerProtocol {
         
         notificationCenter.removeDeliveredNotifications(withIdentifiers: notificationsIdentifiers)
     }
+    
+    private func removeReceivedWhileOfflineNotification() {
+        notificationCenter.removeDeliveredNotifications(withIdentifiers: [NotificationServiceExtension.receivedWhileOfflineNotificationID])
+    }
 
     private func setPusher(with deviceToken: Data, clientProxy: ClientProxyProtocol) async -> Bool {
         do {

ElementX/SupportingFiles/PrivacyInfo.xcprivacy

@@ -166,6 +166,14 @@
 				<string>7D9E.1</string>
 			</array>
 		</dict>
+		<dict>
+			<key>NSPrivacyAccessedAPIType</key>
+			<string>NSPrivacyAccessedAPICategorySystemBootTime</string>
+			<key>NSPrivacyAccessedAPITypeReasons</key>
+			<array>
+				<string>8FFB.1</string>
+			</array>
+		</dict>
 	</array>
 </dict>
 </plist>

NSE/Sources/BootDetectionManager.swift

@@ -8,7 +8,7 @@
 
 import Foundation
 
-enum DataProtectionManager {
+enum BootDetectionManager {
     /// Detects after reboot, before unlocked state. Does this by trying to write a file to the filesystem (to the Caches directory) and read it back.
     /// - Parameter containerURL: Container url to write the file.
     /// - Returns: true if the state detected
@@ -34,4 +34,15 @@ enum DataProtectionManager {
         }
         return false
     }
+    
+    /// The time that the system was booted, as a Unix timestamp.
+    static func systemBootTime() -> TimeInterval? {
+        var bootTime = timeval()
+        var size = MemoryLayout<timeval>.size
+        var managementInformationBase: [Int32] = [CTL_KERN, KERN_BOOTTIME]
+        
+        guard sysctl(&managementInformationBase, 2, &bootTime, &size, nil, 0) == 0 else { return nil }
+        
+        return TimeInterval(bootTime.tv_sec) + TimeInterval(bootTime.tv_usec) / 1_000_000
+    }
 }

NSE/Sources/NotificationServiceExtension.swift

@@ -30,7 +30,13 @@ import UserNotifications
 // notification.
 
 class NotificationServiceExtension: UNNotificationServiceExtension {
+    static let receivedWhileOfflineNotificationID = "io.element.elementx.receivedWhileOfflineNotification"
+    
     private static var targetConfiguration: Target.ConfigurationResult?
+    
+    private static var hasHandledFirstNotificationSinceBoot = false
+    private static let firstNotificationThreshold: TimeInterval = 15 * 60
+    
     private let settings: CommonSettingsProtocol = AppSettings()
     private let appHooks: AppHooks
     
@@ -55,7 +61,7 @@ class NotificationServiceExtension: UNNotificationServiceExtension {
         // the target configuration will fail. We could call exit(0) here, however with the
         // notification filtering entitlement that results in the notification being discarded
         // so we need to wait for the delegate method to be called and bail out there instead.
-        if !DataProtectionManager.isDeviceLockedAfterReboot(containerURL: URL.appGroupContainerDirectory),
+        if !BootDetectionManager.isDeviceLockedAfterReboot(containerURL: URL.appGroupContainerDirectory),
            Self.targetConfiguration == nil {
             Self.targetConfiguration = Target.nse.configure(logLevel: settings.logLevel,
                                                             traceLogPacks: settings.traceLogPacks,
@@ -72,14 +78,30 @@ class NotificationServiceExtension: UNNotificationServiceExtension {
     }
     
     private func handle(_ request: UNNotificationRequest, withContentHandler contentHandler: @escaping (UNNotificationContent) -> Void) async {
-        // If we skipped configuring the target it means we can't write to the app group, so we're unlikely
+        // If we skipped configuring the target it means we can't write to the app group, so we're unlikely to
-        // to be able to create a session (and even if we could, we would be missing the lightweightTokioRuntime),
+        // be able to create a session (and even if we could, we would be missing the lightweightTokioRuntime).
-        // so instead lets deliver the default generic notification and avoid attempting to process the notification.
+        // Additionally, APNs servers only store the most recent notification when the device is powered off.
+        // So lets a) skip processing the notification and b) deliver a special "offline" notification as a workaround.
         guard Self.targetConfiguration != nil else {
             // MXLog isn't configured:
             // swiftlint:disable:next print_deprecation
-            print("Device is locked after reboot, delivering the unmodified notification.")
+            print("Device is locked after reboot.")
-            return contentHandler(request.content)
+            
+            if Self.hasHandledFirstNotificationSinceBoot {
+                return contentHandler(request.content)
+            } else {
+                Self.hasHandledFirstNotificationSinceBoot = true
+                deliverReceivedWhileOfflineNotification(for: request)
+                return contentHandler(.init())
+            }
+        }
+        
+        guard !shouldDeliverReceivedWhileOfflineNotification() else {
+            // Don't log until the app hooks have been run:
+            // swiftlint:disable:next print_deprecation
+            print("Device is unlocked but may have missed notifications while offline.")
+            deliverReceivedWhileOfflineNotification(for: request)
+            return contentHandler(.init())
         }
         
         guard let roomID = request.content.roomID else {
@@ -149,7 +171,73 @@ class NotificationServiceExtension: UNNotificationServiceExtension {
         notificationHandler?.handleTimeExpiration()
     }
     
-    // MARK: - Private
+    // MARK: - Boot handling
+    
+    /// The APNs servers only store the most recent notification when delivery fails. So when the user first boots
+    /// their phone we need to use some approximations to decide whether or not the first notification may potentially
+    /// represent more than one message. When that appears possible we replace the notification's content with the special
+    /// "received while offline" notification as a more prominent prompt for to the user to open the app and check all their chats.
+    ///
+    /// Note that this only handles the first-boot case. When the SDK is able to compute the unread count, we should start to use the NSE,
+    /// remote-notifications (content-available) and background app refreshes to fetch and deliver our notifications as a more robust solution.
+    private func shouldDeliverReceivedWhileOfflineNotification() -> Bool {
+        if Self.hasHandledFirstNotificationSinceBoot {
+            // If we've already handled the first notification in this process there's no need to continue.
+            return false
+        }
+        
+        Self.hasHandledFirstNotificationSinceBoot = true
+        
+        guard let currentBootTime = BootDetectionManager.systemBootTime() else {
+            // There's not much we can do if the boot time is unknown, so don't show the offline notification.
+            return false
+        }
+        
+        guard let lastKnownBootTime = settings.lastNotificationBootTime else {
+            // Assume a missing boot time indicates a fresh installation…
+            // So store the current boot time but let the notification through.
+            settings.lastNotificationBootTime = currentBootTime
+            return false
+        }
+        
+        if abs(lastKnownBootTime - currentBootTime) < 1 {
+            return false
+        }
+        
+        // This is the first notification since boot, store the boot time.
+        settings.lastNotificationBootTime = currentBootTime
+        
+        // At this point it becomes a trade-off. Once the device has been powered on for a long enough amount
+        // of time it is a reasonable assumption that the device has now connected to a network and that any
+        // notification is actually new rather than having been sent whilst the device was powered off.
+        //
+        // Note: We could actually solve this by having Sygnal add a timestamp to the notification payload 🤔
+        if Date.now.timeIntervalSince(Date(timeIntervalSince1970: currentBootTime)) > Self.firstNotificationThreshold {
+            return false
+        } else {
+            return true
+        }
+    }
+    
+    /// Delivers a generic notification informing the user that they have one or more new messages.
+    ///
+    /// Note: it is safe to call this method multiple times as it simply replaces any existing instance of the notification
+    /// with a fresh copy, meaning it won't queue multiple copies but will still re-play the notification sound.
+    private func deliverReceivedWhileOfflineNotification(for originalRequest: UNNotificationRequest) {
+        // This is intended to be called before the app hooks have been run, so don't log:
+        // swiftlint:disable:next print_deprecation
+        print("Delivering the 'received while offline' notification.")
+        
+        let content = UNMutableNotificationContent()
+        content.body = L10n.notificationReceivedWhileOfflineIos
+        content.badge = originalRequest.content.unreadCount as NSNumber?
+        content.sound = .init(named: .init("message.caf"))
+        
+        let request = UNNotificationRequest(identifier: Self.receivedWhileOfflineNotificationID, content: content, trigger: nil)
+        UNUserNotificationCenter.current().add(request)
+    }
+    
+    // MARK: - Logging
     
     private var tag: String {
         "[NSE][\(Unmanaged.passUnretained(self).toOpaque())][\(Unmanaged.passUnretained(Thread.current).toOpaque())][\(ProcessInfo.processInfo.processIdentifier)]"

NSE/SupportingFiles/PrivacyInfo.xcprivacy

@@ -28,6 +28,14 @@
 				<string>7D9E.1</string>
 			</array>
 		</dict>
+		<dict>
+			<key>NSPrivacyAccessedAPIType</key>
+			<string>NSPrivacyAccessedAPICategorySystemBootTime</string>
+			<key>NSPrivacyAccessedAPITypeReasons</key>
+			<array>
+				<string>8FFB.1</string>
+			</array>
+		</dict>
 	</array>
 </dict>
 </plist>