Mobile App Development Last-Minute Revision

30 quick revision notes for Mobile App Development

1. Flutter draws its own UI with the Impeller engine, while React Native renders real native views for each component.
2. Cross-platform suits most API-driven apps; native suits heavy graphics, deep hardware use and day-one platform features.
3. Dart has sound null safety; types are non-nullable by default and String? allows null values.
4. Use const widget constructors so Flutter can reuse instances and skip unnecessary rebuild work.
5. StatefulWidget keeps mutable state in a State object; always dispose controllers and subscriptions in dispose.
6. Keys help Flutter match widgets to state when list items are reordered, inserted or removed.
7. In Flutter, constraints go down, sizes go up, and parents set positions for their children.
8. Use isolates with Isolate.run or compute for CPU-heavy work like parsing very large JSON files.
9. Check context.mounted before using BuildContext after an await, because the widget may be gone.
10. Riverpod is compile-safe and independent of the widget tree; Bloc uses events and states for strict traceability.
11. Bloc and Cubit skip emitting a state equal to the current one, so always emit new immutable objects.
12. go_router supports URL routes, redirects for auth and StatefulShellRoute for tabs with separate stacks.
13. The React Native New Architecture uses JSI, Fabric and TurboModules and is the default since version 0.76.
14. Hermes precompiles JavaScript to bytecode, improving startup time and memory use in React Native apps.
15. Use FlatList or FlashList for long lists in React Native; ScrollView renders every child at once.
16. Keep animations on the UI thread with Reanimated so a busy JS thread does not cause stutter.
17. TanStack Query manages server state with caching, refetching and retries; keep global stores for client state.
18. Expo is the recommended way to start React Native apps and provides EAS Build, Submit and Update.
19. Over-the-air updates can change only JavaScript and assets, never native code or permissions.
20. Never ship real secrets in a mobile app; anything bundled in the binary can be extracted by decompiling.
21. Store tokens in Keychain or Keystore-backed secure storage, never in plain shared preferences or AsyncStorage.
22. Allow only one token refresh at a time and queue other requests to avoid random logouts.
23. Firestore security rules are your backend when apps read and write the database directly.
24. Verify payments on the server using gateway signatures and webhooks, never trust only the client callback.
25. Offline-first apps render from a local database and sync queued changes when the network returns.
26. Push notifications need a device token sent to your backend, and iOS also needs an APNs key configured.
27. iOS crashes if a permission is requested without its usage description string in the Info.plist file.
28. Always measure performance on release or profile builds on real budget devices, not debug builds.
29. Android versionCode and iOS build numbers must increase with every store upload of the app.
30. Use testing tracks, TestFlight and staged rollouts, and monitor crash-free rate before expanding releases.

Night-before checklist

• Revise your saved questions on this page once, aloud.
• Read the quick notes and mark any you cannot explain in one line.
• Rehearse a two-minute self-introduction and two project stories.
• Keep CV, ID, laptop charger and interview link ready; sleep on time.