Guide
MOBILE INTERVIEW Qs
Technical questions and model answers for interviewing mobile developers. Covers native vs cross-platform, Flutter, app store submission, push notifications, and offline-first architecture.
Last updated: May 2026
Explain the tradeoffs between native and cross-platform development
Native development offers full platform API access, best performance, and native UI/UX, but requires separate codebases for iOS and Android. Cross-platform (Flutter, React Native) covers both OSs from a single codebase with faster development and easier maintenance. However, advanced custom UIs or cutting-edge OS features may require native modules.
What are the differences between Flutter and React Native, and which projects suit each?
Flutter is written in Dart and has its own rendering engine (Skia/Impeller), so it draws the same UI pixel-by-pixel on any OS. It excels at apps with heavy custom UIs or game-like animations. React Native uses JavaScript/TypeScript and native components, so it blends naturally with the OS's standard UI. It's ideal for projects that can leverage a web team's expertise or an existing React ecosystem.
What should you watch out for during App Store and Google Play submission?
The App Store has a strict review process and may reject apps for guideline violations such as misleading descriptions, non-functional features, or improper permission usage. Prepare accurate screenshots, privacy policies, and sign-in feature descriptions. Google Play has a more relaxed review but has recently strengthened privacy and security checks. On both stores, app size, launch time, and crash rate affect ratings and visibility.
What technical points should be considered when implementing push notifications?
Understand the differences between FCM and APNs, and manage device tokens properly. Pay attention to background vs foreground behavior, notification priority and channels (Android), rich notifications (images, buttons), and badge count management. Also important: distinguishing local from remote notifications, and choosing the optimal timing for the user's permission dialog.
Describe the design principles of an offline-first architecture
In offline-first architecture, the local database (SQLite, Realm, Room, Hive, etc.) is the single source of truth, and server sync happens in the background. Use optimistic UI to give immediate feedback, and define a conflict resolution strategy upfront. Monitor network state, implement retry queues, and use delta sync to save bandwidth and battery.
List the key performance metrics and optimization techniques for mobile apps
Key metrics: launch time (cold start < 2s), frame rate (maintain 60fps), memory usage, binary size, battery consumption, and crash rate. Optimization techniques: convert images to WebP with lazy loading, virtualize lists (RecyclerView / ListView.builder), prevent unnecessary rebuilds (const constructors, memoization), use native code (NDK/JNI) appropriately, and measure regularly with profilers like Android Studio Profiler and Xcode Instruments.
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