Mobile Project Management App with Offline Synchronization

A manager jots down tasks in a notebook during a meeting, then transfers them to Trello—by then, colleagues are already working with outdated data. Our solution: a mobile app with offline-first synchronization that instantly syncs changes even without internet. We develop for iOS and Android, backed by 30+ projects and a 3-month warranty. Key features: Kanban, push notifications, time tracking, and Gantt chart.

Problems We Solve

Offline editing conflicts. Two users change a task status without network. We apply Last-Write-Wins with timestamps; for complex scenarios, we use Operational Transformation (as in Notion). This prevents data loss with 1000+ concurrent users.

Intrusive push notifications. Constant alerts reduce productivity. We implement contextual logic: @mentions immediately, assignments immediately, deadline changes to the assignee, deadline within 24 hours—reminder. Users customize notification types in profile—settings sync across devices. According to our stats, this boosts retention by 25%.

Mobile Kanban. Drag-and-drop between columns is technically tricky due to gesture conflicts. Our approach: tap → bottom sheet (Android) or context menu (iOS) to select status. Simpler but reliable on any device. On iOS we use UIContextMenuConfiguration (iOS 13+), on Android—ItemTouchHelper with simplified D&D.

How We Do It

Typical architecture: Workspace → Project → Board → Task → Subtask → Comment. Local storage: Room or Core Data. Server sync via REST/GraphQL. Our approach to pricing is transparent: we estimate after analyzing your requirements, so you only pay for what you need.

// Android — pending operations queue
class TaskRepository(
    private val taskDao: TaskDao,
    private val pendingOpsDao: PendingOperationDao,
    private val api: ProjectApi
) {
    suspend fun updateTaskStatus(taskId: String, newStatus: TaskStatus) {
        taskDao.updateStatus(taskId, newStatus)
        val op = PendingOperation(
            type = OperationType.UPDATE_TASK_STATUS,
            entityId = taskId,
            payload = json.encodeToString(mapOf("status" to newStatus.name))
        )
        pendingOpsDao.insert(op)
        if (networkMonitor.isConnected) syncPendingOperations()
    }
}

For iOS—similar with Core Data and NSBackgroundActivityScheduler. Smart push notifications subscribe via APNs/FCM; filtering logic lives on the server.

Why Push Notifications Shouldn't Be Annoying?

Constant notifications break focus. We implement a priority system: high—@mention, task assignment, deadline change; medium—status changed (only for watchers); low—scheduled reminder 24 hours before deadline. The client stores settings in the server-side profile, so they persist after app reinstall. This improves retention and keeps users happy.

Gantt Chart Implementation Approaches

We recommend native rendering for projects with hundreds of tasks—it ensures smooth scroll and zoom, though it requires more development time.

What's Included in the Work

After project completion, you receive:

• Source code under NDA;
• Architecture documentation (diagrams, stack description);
• Configured CI/CD (GitHub Actions + Fastlane);
• Access to App Store Connect and Google Play Console;
• Team training (2-3 sessions);
• 3-month warranty for defect fixes.

Timelines

MVP (tasks, Kanban, push, offline): from 8 to 12 weeks. Full set: 16–20 weeks. Interested in an estimate for your project? Get a consultation—we'll provide details tailored to your stack.

How to Ensure Conflict-Free Synchronization During Offline Work?

The key is a pending operations queue with idempotency keys and a retry mechanism. On the server—validate changes by entity version (optimistic locking). On the client—show sync status (green/yellow/red icon). This way users know the state of their data. We use this approach in all projects—proven under load up to 1000 concurrent users. We guarantee stable operation thanks to our experience with high-load systems.

Request an audit of your project—we'll propose the optimal solution. Ready to discuss your task? Contact us for a preliminary estimate.

Push Notifications in Mobile App: APNs, FCM, Segmentation, Rich Push

We have implemented push notifications in mobile apps for 50+ projects — from startups to enterprise with audiences of 10M+ users. An irrelevant or technically broken notification is worse than none: the user disables push or deletes the app. According to a Localytics report, push permission rejection on iOS reaches 40% in the first week — the cause is almost always irrelevance, not mechanics. Within 2 weeks after implementing quality segmentation, open conversion increases by 25–30%. Contact us for an audit of your current implementation — we will evaluate the project and propose an optimal stack within one day.

How the Infrastructure Works: APNs and FCM

APNs is the only delivery channel on iOS. Everything else (OneSignal, Braze, Airship) is a wrapper on top of it. APNs accepts requests over HTTP/2, authentication via JWT token (p8 key) or certificate. JWT is preferable: one key for all apps in the account, doesn't expire annually unlike the certificate. For more details, see the official documentation.

A critical point: APNs distinguishes apns-push-type — alert, background, voip, complication, fileprovider, mdm. An incorrect type on iOS 13+ causes background notifications not to wake the app. We've seen projects where content-available: 1 was sent without apns-push-type: background — the app didn't receive silent push on some devices, and the team spent a month looking for an 'app bug'.

FCM on Android works through Google Play Services. For devices without GMS (Huawei, part of the Chinese market), Huawei Push Kit or a direct WebSocket is needed — a separate task. FCM supports data messages (handled in onMessageReceived) and notification messages (the system displays automatically if the app is in the background). Mixing them requires caution: if the notification block has a click_action but the deep link is not registered in the app, tapping the notification simply opens the main screen without navigation.

Why Segmentation Is the Foundation of Effective Push Notifications?

Sending to everyone indiscriminately quickly exhausts user loyalty. Personalized messages are clicked 3 times more often than bulk ones, and proper segmentation reduces churn by 25% (on one project it brought significant additional revenue per quarter). The cost of setting up segmentation in OneSignal or a custom backend depends on the complexity of filters.

Proper segmentation is built on several levels.

Topics are for broad categories: 'new promotions', 'order status updates'. User subscribes via FirebaseMessaging.getInstance().subscribeToTopic("orders"). Simple, but no flexible filtering.

Attribute-based segments — via OneSignal, Braze, or custom backend. We store in the user profile: language, device type, last activity, LTV segment. Notification goes only to those with last_active < 7_days and plan = premium. OneSignal allows building such filters in the interface without code.

Personalized — by specific device_token. It's important to store tokens correctly: the token updates on app reinstall, restoration from backup on a new phone, or resetting settings. On iOS, use UNUserNotificationCenter + didRegisterForRemoteNotificationsWithDeviceToken, save to backend on every launch, not just the first. Otherwise, after 3 months 30% of tokens in the database are outdated.

What Is Rich Push and How Does It Boost Conversion?

A standard notification with title and text is clicked less often than a rich push with image and action buttons — by 3 times. But implementing rich push is a separate task on each platform.

On iOS, rich content requires UNNotificationServiceExtension (to modify payload) and UNNotificationContentExtension (custom UI). The extension runs in a separate process with limited time and memory. If the extension crashes or exceeds the timeout, the system shows the original payload without media. A typical mistake is trying to load an image over HTTP (not HTTPS): ATS blocks the request, the extension silently fails, and the user sees a notification without an image.

On Android with API 26+, notifications are tied to NotificationChannel. If the channel is created with IMPORTANCE_LOW, sound and vibration are unavailable. Different notification types (transactional, marketing) should be in different channels so the user can disable marketing without losing order notifications. BigPictureStyle, MessagingStyle, InboxStyle are templates for expanded notifications. MessagingStyle with Person and avatars is the best choice for chats.

How to Track Delivery and Conversion of Push Notifications?

Sending a notification is half the work. It's important to know: was it delivered, opened, and did it lead to a target action.

FCM returns a MessageId on send, but does not guarantee a delivery callback — by design. For open tracking, custom logic is needed: on notification tap in onMessageReceived or via getInitialNotification() / onNotificationOpenedApp (OneSignal SDK), send an event to analytics with notification_id.

OneSignal provides built-in delivery and CTR analytics. For more detailed analysis — integrate with Amplitude or Mixpanel via webhook on open events. The budget for such a dashboard varies depending on event volume.

How We Implement Push Notifications: Typical Process

1. Audit current implementation — check token storage, update handling, notification types.
2. Design architecture — choose transport (FCM + APNs), segmentation layer (OneSignal/Braze/custom), personalization method.
3. Implementation — write registration code, inbound handling, rich push, deep linking.
4. Testing — send test campaigns, verify delivery on different devices, simulators, regions.
5. Monitoring and analytics — set up dashboard, open and conversion events.
6. Documentation and training — hand over operational materials to the team.

Typical stack: FCM + APNs at transport level, OneSignal or Firebase Notifications Composer for segmentation, custom backend for personalized event-based notifications. For large apps with >1M users, OneSignal has pricing limits — then we use Braze or a custom implementation on AWS SNS.

Timelines depend on complexity: basic FCM+APNs integration with transactional notifications — 1–2 weeks. A full system with segmentation, rich push, analytics, and A/B testing — 4–8 weeks. Order an audit of your current push infrastructure or get a consultation on implementing push notifications in your mobile app — we will contact you within a day and provide an accurate estimate.