Mock camera modules in unit tests, use jest.mock(), write unit tests for logic only, and use E2E tools like Detox or Appium with mocked camera feeds

Test camera functionality by accessing the real device camera in all tests

Avoid testing components that use camera access

Test only on physical devices without mocks

How should you test a React Native component that uses camera functionality?

This test assesses knowledge of React Native development scenarios, debugging, architecture, and best practices for building scalable, secure, and performant applications.

Use libraries like react-native-keychain or expo-secure-store, avoid AsyncStorage for sensitive data

Store tokens in plain text in AsyncStorage

Save tokens directly in JavaScript variables

Which method is considered secure for storing tokens and sensitive user data in a React Native app?

Check Proguard rules and ensure native configurations are correct

If your React Native app crashes only in the Android release build but works fine in debug mode, what is the first step you should take to identify the cause?

Use react-navigation stack navigator with conditional navigation logic and manage state via Context or local state

Create separate apps for each onboarding step

Load all onboarding screens simultaneously without conditional logic

How can you implement a 5-step onboarding flow with navigation that depends on the user's input in React Native?

Use profiling tools like Flipper or Android/iOS profilers, and clean up event listeners and intervals in useEffect cleanup functions

Ignore the problem since it only occurs sometimes

Use infinite loops inside modals to keep memory occupied

What is a recommended approach to identify and fix memory leaks caused by repeatedly opening and closing modals in a React Native app?

Use WebSockets (e.g., socket.io-client or Firebase Realtime Database) connected in useEffect with event listeners, debounce indicators, and proper cleanup

Refresh the entire chat screen every minute

Send chat messages as SMS via a third-party service

To efficiently handle real-time chat updates in a React Native app, which technology stack and handling approach is recommended?

Use FlatList with windowSize and removeClippedSubviews, avoid inline render functions, use optimized image libraries, and only play one video at a time

Load all media elements at once without optimization

Use deprecated ListView component instead of FlatList

When a React Native feed screen drops frames while scrolling videos and images, what optimization methods should be applied?

Manage theme state globally with Context or Zustand, define global theme tokens, consume them via useContext, and persist preference in AsyncStorage

Manually set dark styles on each component without centralized management

Create separate apps for light and dark themes

Use inline styles with no state management

What is an effective approach to implement dark mode with runtime switching across many React Native components?

Use tools like Nx, Turborepo, or Lerna, organize code into modular packages (e.g., @app/mobile, @shared/ui), apply TypeScript project references, and use CI workflows targeting affected packages

Keep all code in a single large folder without division

Develop separate repositories without shared code

Use only JavaScript without TypeScript in a monolithic project

How would you structure a monorepo for scaling a React Native app to support multiple teams working on shared and mobile-specific code?

Verify APNs key setup, enable push notification capabilities and background modes in Xcode, ensure correct payload format, and log device tokens/errors

Assume iOS doesn’t support push notifications

If push notifications work on Android but fail silently on iOS, what should you check first?

Configure linking in react-navigation, add intent filters in AndroidManifest.xml, configure Associated Domains and apple-app-site-association file on iOS, and parse paths correctly

Use only Android deep links and ignore iOS

Rely on manual navigation without deep linking

Which steps are essential to support deep links and universal links in a React Native app on both Android and iOS?

Handling unsupported native modules, migrating config files to app.json, adapting OTA update strategy with Expo Updates, and managing CI/CD changes due to Expo's build service

Expo supports all native modules without exceptions

No changes are needed; migration is fully automatic

Native modules become more compatible without effort

What challenges should you anticipate when migrating a React Native CLI app to Expo?

Use react-native-fast-image for caching, downscale images, monitor memory via Android Profiler, use dynamic image sizing, and implement lazy loading

Load all high-resolution images at once without caching

Increase image resolutions to highest possible

How can you reduce crashes in an Android app on low-RAM devices during image-heavy flows?

Use libraries like react-native-keychain or expo-local-authentication, check hardware availability, unlock credentials using biometrics, provide PIN/password fallbacks, and handle permission rejections gracefully

Ignore fallback methods and only use biometrics

Implement biometrics without checking device compatibility

Store biometric data directly in AsyncStorage

What is the recommended plan to implement biometric authentication (FaceID/Fingerprint) in a React Native application?

Wrap the SDK using Native Modules in Java (Android) and Swift/Obj-C (iOS), register and expose APIs to JavaScript, and write tests for the bridge

Discard the SDK and implement the feature manually

How can you integrate a third-party native SDK that doesn’t natively support React Native?

Implement a versioning system for storage, save version keys, run migration logic conditionally, back up key data, and avoid key collisions

Ignore version conflicts and overwrite data blindly

Delete all AsyncStorage data after each update

Store data only in memory without persistence

What is a good strategy to handle AsyncStorage migration issues and prevent data loss after app updates?

Check for missing or misconfigured apple-app-site-association file, mismatched App ID, missing Associated Domains entitlement, lack of HTTPS, and use Apple validation tools

Disable Associated Domains entitlement to fix the issue

When deep links work on Android but not on iOS, what are common misconfigurations to check?

Enable RTL via I18nManager, update styles to use flexDirection 'row-reverse' or start/end, use internationalization libraries, and ensure component flip options are respected

Ignore text direction and rely solely on left-to-right layouts

Manually flip screens without changing style properties

Use inline styles only without enabling RTL globally

What must you do to support RTL (Right-to-Left) languages such as Arabic or Hebrew in React Native?

Move UI-specific state like modals and spinners to component state (useState) or Context, reserve Redux for shared business state, and split reducers into domains with selectors

Add all UI state to Redux without separation

If a Redux store becomes bloated with too much UI-related temporary state, what refactoring strategy should you use?

Prevent exposing sensitive keys in JS bundles, manage native vs. JS version conflicts carefully, prepare for rollout rollback strategies, and monitor app versions with update logs

Push all updates directly without version management

Ignore native code changes and update only JS files

Deploy updates manually via app stores only

What are key challenges when implementing Code Push (OTA updates) in a React Native app, and how should you handle them?

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