Recruiter’s Questions

1. What testing strategies do you typically employ for mobile applications?

Great Response: "I implement a comprehensive testing pyramid approach. At the base, I write unit tests for individual components and business logic with frameworks like XCTest or JUnit, aiming for at least 80% coverage of non-UI code. In the middle tier, I create integration tests to verify component interactions. For UI testing, I use XCUITest or Espresso for automated flows. I also implement snapshot testing for UI components to catch visual regressions. Before release, I conduct manual exploratory testing focusing on edge cases and user journeys that are difficult to automate. Throughout development, I use CI pipelines to run these tests automatically on each commit to catch issues early."

Mediocre Response: "I typically write unit tests for the core functionality and run manual tests on the UI before submitting a PR. I try to test the main user flows manually on a few different device sizes. For critical features, I might add UI tests using XCUITest or Espresso. I usually aim for around 60% test coverage, focusing on the most important parts of the app."

Poor Response: "I generally rely on manual testing to verify my features work as expected. I'll run through the feature on my development device a few times to make sure it's working. Sometimes I'll write unit tests if I have time, but I usually trust the QA team to find any issues. I find that automated tests often break during rapid development cycles, so I focus more on shipping code and fixing issues when they're reported."

2. How do you approach optimizing app performance on mobile devices?

Great Response: "I start with benchmarking key metrics like startup time, memory usage, and UI responsiveness. For iOS, I use Instruments to profile CPU, memory, and network usage; for Android, Android Profiler. I optimize rendering by flattening view hierarchies, reusing cells/views, and implementing pagination for long lists. I minimize main thread work by moving heavy operations to background threads using GCD/Dispatch Queues or Kotlin Coroutines. For network optimization, I implement caching strategies, compress payloads, and batch requests when possible. I also use image loading libraries that efficiently handle caching and downsampling. Finally, I establish performance budgets for key screens and monitor metrics continuously through the development process, not just at the end."

Mediocre Response: "When I notice performance issues, I check for memory leaks using the profiler tools and fix any obvious problems. I try to follow best practices like recycling views in lists and not doing network calls on the main thread. I'll cache images and API responses when possible. If a particular screen feels sluggish, I'll look for optimization opportunities like reducing layout complexity or implementing view recycling."

Poor Response: "I optimize when users or QA report slowdowns. My main approach is to use the built-in libraries and components provided by the platform, as they're usually already optimized. For images, I use libraries like Glide or SDWebImage to handle loading. If performance becomes an issue, I'll usually look online for the recommended solution for that specific problem. Modern phones are pretty powerful these days, so performance is rarely a major concern unless you're doing something very intensive."

3. Explain your approach to implementing secure authentication in a mobile app.

Great Response: "I implement authentication using industry standards like OAuth 2.0 with OpenID Connect for a secure and maintainable solution. I store sensitive tokens in the Keychain (iOS) or EncryptedSharedPreferences (Android), never in regular preferences or local storage. I implement certificate pinning to prevent man-in-the-middle attacks. For biometric authentication, I use the platform's secure APIs (FaceID/TouchID or Biometric Prompt). I ensure tokens have proper expiration and implement secure refresh mechanisms. I also handle edge cases like device jailbreak/root detection and implement rate limiting for authentication attempts. Finally, I make sure to sanitize logs to prevent sensitive data exposure and follow OWASP Mobile Top 10 guidelines for security best practices."

Mediocre Response: "I typically integrate with authentication libraries or SDKs provided by the backend team or use popular solutions like Firebase Authentication. I store the authentication token securely and include it in API requests. For added security, I'll implement biometric authentication if required. I make sure to clear credentials when users log out and handle session expiration by prompting users to log in again."

Poor Response: "I usually implement the login screen according to the design, then send the username and password to the authentication endpoint provided by the backend team. Once I get back a token, I store it in the app's preferences and include it in the header of all API requests. If the API returns an authentication error, I redirect the user to the login screen again. I rely on HTTPS for securing the data in transit and trust the backend team to handle the server-side security aspects."

4. How do you handle responsive UI design across different screen sizes and orientations?

Great Response: "I start with a device-agnostic design system using relative measurements and breakpoints. In iOS, I use Auto Layout with stack views and size classes to define adaptive layouts. On Android, I implement ConstraintLayout with percentage-based constraints and create multiple dimension resources for different screen sizes. I avoid hardcoded dimensions, using dynamic text sizing and scalable assets (vector drawables/PDF). I test on multiple device sizes and orientations throughout development using the simulator/emulator matrix and physical devices. For complex screens, I create separate layouts for phone vs. tablet when necessary. I also consider platform-specific patterns – for example, using bottom navigation on Android and tab bars on iOS – while maintaining a consistent overall experience."

Mediocre Response: "I use Auto Layout on iOS and ConstraintLayout on Android to create flexible layouts that adapt to different screen sizes. I test my layouts on both phone and tablet simulators to make sure they look correct. I avoid hardcoding pixel values and instead use the platform's recommended units like dp on Android or UIKit's dynamic type on iOS. For particularly troublesome layouts, I sometimes create alternative layouts for different size classes."

Poor Response: "I design the UI for the most common screen size first, usually the latest iPhone or a standard Android phone like a Pixel. I use the visual layout tools in Android Studio or Xcode to place elements and then test on a few different simulators to catch any obvious layout issues. If something breaks on a specific device, I add special handling for that case. I rely heavily on the built-in layout systems to handle most of the responsiveness automatically."

5. Describe your experience with offline functionality and data synchronization in mobile apps.

Great Response: "I've implemented comprehensive offline-first architectures using a local database (Realm, Room, or CoreData) as the single source of truth. I structure the app to always read from local storage and implement repository patterns to abstract data sources. For sync, I use a combination of timestamp-based and logical clock approaches depending on the complexity of data relationships. I handle conflict resolution by implementing custom merge strategies for different data types and maintaining a queue of pending operations that retry automatically when connectivity is restored. I also implement background sync using WorkManager on Android or Background Tasks on iOS, with exponential backoff for retries. To minimize data usage, I use delta updates where possible and provide users with control over when syncing occurs, especially for large media files."

Mediocre Response: "I've worked with offline functionality by caching API responses in a local database like SQLite or Realm. The app checks for network connectivity and falls back to cached data when offline. When the connection is restored, the app syncs local changes with the server. For simple cases, I track which entities have been modified while offline and send updates when back online. I handle basic conflicts by usually letting the server decide which version is correct."

Poor Response: "I've implemented basic offline functionality by saving important data to local storage, like user preferences or recent items. I usually show an error message when the app is offline and certain features aren't available. For data that needs to be submitted while offline, I save it locally and add a retry button that the user can tap when they have connectivity again. I generally focus on making sure the app doesn't crash when there's no internet rather than building complex offline functionality."

6. How do you manage dependencies and third-party libraries in your mobile projects?

Great Response: "I take a strategic approach to dependency management, starting with careful evaluation of any library against criteria like active maintenance, community support, code quality, and performance impact. I use dependency managers like CocoaPods/Swift Package Manager or Gradle with defined version constraints to prevent unexpected updates. For critical dependencies, I fork or vendor the code to ensure long-term availability. I regularly audit dependencies for security vulnerabilities using tools like npm audit or dependency-check and update them on a regular schedule to balance stability with security. I also maintain a dependency inventory documenting why each library was chosen and follow a 'less is more' philosophy, only adding libraries when they provide significant value over custom implementations. Finally, I write abstraction layers around third-party code to make future replacements easier."

Mediocre Response: "I use CocoaPods for iOS or Gradle for Android to manage dependencies. When I need functionality that would take a lot of time to build, I look for popular libraries on GitHub that solve the problem. I check the star count, last commit date, and issue list to make sure it's maintained. I specify exact versions in the dependency file to avoid unexpected breaking changes and update libraries periodically when new features are needed or security issues are announced."

Poor Response: "I add libraries through the package manager when I need to solve a specific problem quickly. I usually go with the most popular option on GitHub or what's recommended in blog posts and tutorials. I typically use the latest version to get all the new features and bug fixes. If a library starts causing problems, I'll look for an alternative or remove it. I don't spend too much time evaluating libraries since you can always change them later if needed."

7. What strategies do you use to reduce app size and optimize download times?

Great Response: "I implement a multi-faceted approach to size optimization. I use app bundles (Android App Bundle/iOS App Thinning) to deliver device-specific resources. I compress and convert images to efficient formats like WebP and use vector drawables where possible. For code optimization, I enable ProGuard/R8 on Android for code minification and use the Xcode size report to identify large assets or libraries on iOS. I implement on-demand resources or dynamic feature modules for content that isn't needed at launch. I regularly analyze the app using size reporting tools and perform comparative analysis between versions to catch size regressions. I've also implemented deferred loading strategies for non-critical SDKs and set up size budgets with automated checks in CI. When appropriate, I'll use platform-specific optimizations like asset catalogs in iOS or density-specific resources in Android."

Mediocre Response: "I optimize app size by compressing images and using vector drawables when possible. I enable ProGuard on Android to remove unused code and try to avoid including large libraries unless necessary. I use app bundles on Android and app thinning on iOS to deliver optimized builds for each device. I periodically check the app size in the release build and look for opportunities to reduce it."

Poor Response: "I try not to add unnecessary libraries and use image compression tools before adding assets to the project. If the app gets too large, I'll look at what's taking up space and see if there are smaller alternatives. Most users have plenty of storage space these days, so I focus more on making sure the features work well. If size becomes a real issue, I'll look up optimization techniques specific to whatever is causing the bloat."

8. How do you handle API versioning and backward compatibility in your mobile apps?

Great Response: "I implement a robust versioning strategy starting with API version headers in all requests and structured backward compatibility handling. In the app, I use a repository pattern with version-specific adapters that normalize responses across API versions. I implement feature flags tied to API capabilities to progressively enable new features. For major API changes, I maintain parallel implementation paths with graceful degradation for older versions. On the client side, I use semantic versioning for the app itself and enforce minimum API version requirements with user-friendly upgrade prompts. I work closely with the backend team to establish deprecation policies and transition periods. During development, I test against multiple API versions to ensure compatibility, and I monitor analytics to know when we can safely drop support for older versions based on user adoption patterns."

Mediocre Response: "I include the API version in the request headers or URL path and handle any differences in the response format in my network layer. When the backend team updates the API, I update my models and parsers to handle both the old and new formats during the transition period. I try to maintain backward compatibility for at least one or two app versions to give users time to update. For major API changes, I might add logic to detect the API version and adapt the app's behavior accordingly."

Poor Response: "I usually work with whatever API version the backend team provides and update my app to match their latest changes. When they make breaking changes, I update my models and network calls accordingly and release a new app version. I typically focus on supporting the current API version and encourage users to update to the latest app version. If there are compatibility issues with older app versions, I work with the backend team to help them understand what changes would break existing apps."

9. Explain your approach to implementing and managing app navigation.

Great Response: "I implement navigation using a coordinator/flow controller pattern that centralizes navigation logic outside of view controllers/activities. This promotes reusability and testability of screens. I use platform-recommended navigation components like Navigation Component on Android or Coordinator pattern with UIKit, and SwiftUI's NavigationView with router objects. I structure navigation as a state machine, explicitly defining possible transitions between screens and handling deep links consistently with normal navigation flows. For complex apps, I implement modular navigation with each feature module defining its own routes but exposing a public API for cross-module navigation. I also implement analytics tracking at the navigation layer to understand user flows and make navigation interactions accessible, supporting voice control and screen readers."

Mediocre Response: "I use the Navigation Component on Android or UINavigationController on iOS to handle most navigation. I define a navigation graph that shows all the screens and how they connect. For sharing data between screens, I use safe args on Android or prepare segues on iOS. I handle deep links by mapping them to the appropriate destinations in my navigation graph. For complex flows, I might create separate coordinators or flow controllers to manage the sequence of screens."

Poor Response: "I follow the standard patterns for each platform – Intents and Activities on Android or Storyboards and segues on iOS. I use the built-in back button handling and pass data between screens using intent extras or by preparing for segues. When I need to return data to a previous screen, I use activity results or delegate patterns. I focus on making sure users can get where they need to go and that the back button behaves as expected."

10. How do you debug and fix crashes in production apps?

Great Response: "I implement a multi-layered approach to crash management. I integrate comprehensive crash reporting tools like Firebase Crashlytics or Bugsnag that capture device information, user journeys, and custom events leading up to crashes. I set up proactive alerting for crash spikes and implement breadcrumb logging for context. When investigating, I first reproduce the issue in a controlled environment using the crash report data, then use platform-specific debugging tools like Memory Graph Debugger in Xcode or CPU Profiler in Android Studio. For hard-to-reproduce issues, I implement staged rollouts with feature flags to control exposure and add enhanced logging for affected users. I prioritize crashes by impact using both frequency and user-facing severity. After fixing, I validate with targeted regression testing and monitor post-release to confirm resolution. I also maintain a crash knowledge base to track patterns over time."

Mediocre Response: "I integrate crash reporting tools like Crashlytics in all my apps to get stack traces and device information. When crashes occur, I analyze the stack traces and device metadata to understand the conditions that caused the crash. I try to reproduce the issue on a similar device or simulator, then use the debugger to find the root cause. For difficult crashes, I might add additional logging around the problematic area and release an update to gather more information. After fixing the issue, I make sure to add tests to prevent regression."

Poor Response: "I check the crash reports from the App Store/Google Play Console or our crash reporting tool to see what's happening. I focus on the most frequent crashes first and look at the stack traces to identify where they're occurring. If I can understand the cause from the reports, I fix it directly. If not, I add more error handling around the problematic area to prevent the app from crashing even if something goes wrong. Sometimes I'll ask QA to try to reproduce the crash on different devices so I can debug it more effectively."

11. Describe your experience with push notifications and background processing.

Great Response: "I've implemented comprehensive push notification systems using both platform-specific (APNs, FCM) and cross-platform solutions. I design notification architectures with proper categorization, user preference controls, and deep linking to relevant content. For rich notifications, I've created custom interfaces with action buttons and media attachments. On the backend integration side, I've worked with both direct API integration and third-party services like OneSignal, implementing delivery receipts and analytics tracking. For background processing, I use WorkManager on Android and BackgroundTasks on iOS to handle tasks like data synchronization, content prefetching, and scheduled operations with proper battery optimization. I implement exponential backoff for retries and ensure all background work is idempotent. I also carefully manage permissions with progressive permission requests and graceful degradation when permissions are denied."

Mediocre Response: "I've integrated push notifications using Firebase Cloud Messaging for Android and APNs for iOS. I handle the device token registration during app startup and implement notification handlers to respond when the user taps a notification. For background processing, I use services on Android or background fetch on iOS to perform periodic tasks like syncing data when the app isn't active. I make sure to follow platform guidelines to avoid excessive battery usage and provide settings for users to control notification preferences."

Poor Response: "I've added push notifications to apps by following the standard integration guides for FCM and APNs. I send the device token to our backend and display the notifications when they arrive. For background work, I try to do most processing when the app is in the foreground, but sometimes use background services on Android or background modes on iOS when needed. I typically rely on the backend team to handle the sending logic and focus on making sure the app can receive and display the notifications properly."

12. How do you ensure code quality and maintain consistent practices across a mobile codebase?

Great Response: "I employ a multi-faceted approach to code quality. I establish and document coding standards with the team, incorporating platform-specific best practices and team preferences. I set up automated enforcement using linters (SwiftLint, ktlint, ESLint) and formatters integrated with the build process and IDE. For architectural consistency, I create reusable templates and components, and document architectural patterns with sample implementations. I implement a tiered code review process with automated checks for basic issues and focused human reviews for logic and design. I regularly conduct internal knowledge sharing sessions and maintain a team wiki with examples of patterns and anti-patterns. I also track code quality metrics like test coverage, complexity, and technical debt, and allocate regular time for refactoring and tech debt reduction. For larger teams, I create feature development checklists that include security, accessibility, and performance considerations."

Mediocre Response: "I follow a consistent architectural pattern like MVVM or Clean Architecture and use code reviews to ensure everyone adheres to it. I set up static analysis tools like SonarQube or SwiftLint to catch common issues automatically. I try to write unit tests for business logic and use descriptive naming conventions. For team alignment, I participate in code reviews and discuss best practices in team meetings. When I notice inconsistencies, I'll refactor code to match the team's agreed standards."

Poor Response: "I try to follow the existing patterns in the codebase and maintain consistency within the features I work on. I use the built-in code formatting tools in Android Studio or Xcode to keep the code neat. During code reviews, I look for obvious issues and make sure the code is understandable. If there's no established pattern for something new, I'll research best practices online and implement what seems most appropriate. I focus on making sure the code works correctly first, then clean it up if there's time."

13. How do you handle memory management in mobile applications?

Great Response: "I take a proactive approach to memory management, starting with architectural choices that prevent common issues like retain cycles in iOS (using weak references and unowned properly) or context leaking in Android. I use memory profiling tools like Xcode's Memory Graph Debugger or Android Profiler regularly throughout development, not just when problems occur. For image handling, I implement downsampling, caching strategies, and on-demand loading with proper cleanup. I optimize collection views/recycler views with cell reuse and efficient loading patterns. For large data sets, I implement pagination and data windowing techniques. I set up automated memory testing using UI tests with memory snapshots to catch regressions. I also track key metrics like memory growth during extended use sessions and implement memory pressure handling by clearing caches when receiving low memory warnings. For specific use cases like image processing or AR, I implement custom memory management with manual resource disposal."

Mediocre Response: "I pay attention to potential memory leaks, especially with closures in Swift or anonymous inner classes in Java. I use weak references when appropriate and make sure to clean up resources in lifecycle methods like viewDidDisappear or onDestroy. For images, I use libraries that handle efficient loading and caching. When working with large collections, I implement proper cell reuse and avoid keeping unnecessary references. If I notice slowdowns or crashes, I use the memory profiler to identify leaks or excessive allocations and fix them."

Poor Response: "I rely mostly on ARC on iOS and garbage collection on Android to handle memory automatically. I make sure to set objects to null when I'm done with them, especially for larger resources. If I notice the app getting slow or crashing due to memory issues, I'll use the profiler to find what's using too much memory and fix those specific problems. I use image loading libraries that handle memory efficiently for images. Modern devices have plenty of RAM, so I focus more on correctness and features unless memory becomes a noticeable problem."

14. Explain your experience with implementing animations and transitions in mobile apps.

Great Response: "I approach animations with both technical excellence and user experience in mind. I implement animations using native frameworks like UIViewPropertyAnimator or MotionLayout for complex choreographed transitions, and layer animations or property animators for simpler effects. I follow platform guidelines for timing and easing functions to ensure animations feel native. For performance, I focus on animating only compositor-friendly properties like transform and opacity, using tools like Core Animation Instruments or GPU rendering profiling to identify and fix jank. I organize animations into reusable systems aligned with the app's design language and implement state-driven animations that handle interruptions gracefully. For custom effects, I use techniques like custom CALayers or Canvas drawing with optimized rendering paths. I also ensure accessibility by respecting reduced motion settings and providing alternative experiences for users who disable animations."

Mediocre Response: "I use the platform's animation APIs like UIView.animate on iOS or ObjectAnimator on Android for most transitions. For more complex animations, I might use libraries like Lottie for predefined animations created by designers. I try to keep animations subtle and purposeful, focusing on transitions between screens and state changes that help users understand what's happening. I test animations on lower-end devices to make sure they remain smooth and adjust as needed."

Poor Response: "I implement basic animations using the standard platform APIs when required by the design. For simple transitions, I use the built-in options like slide or fade animations between screens. If designers provide more complex animation requirements, I'll look for libraries that can help implement them efficiently. I focus on getting the core functionality working first, then add animations if there's time. Sometimes I'll simplify complex animations if they're causing performance issues on certain devices."

15. How do you approach building accessible mobile applications?

Great Response: "I integrate accessibility throughout the development lifecycle, starting with accessibility requirements in planning. I structure layouts for proper screen reader navigation by using semantic elements and setting accessibility labels, hints, and traits/roles appropriately. I implement keyboard and switch control navigation with logical focus order and visible focus indicators. For touch targets, I ensure they meet size guidelines (at least 44×44 points on iOS, 48×48dp on Android) with adequate spacing. I support dynamic text sizing with scalable layouts and test with larger text sizes. I implement proper color contrast (at least 4.5:1 for normal text) and provide non-color indicators for information. I test regularly with actual screen readers (VoiceOver/TalkBack) and other accessibility tools using both automated checks and manual testing workflows. I also create accessibility test cases and documentation to ensure ongoing compliance and educate team members about accessibility requirements and techniques."

Mediocre Response: "I make sure to add content descriptions to all important UI elements so screen readers can announce them properly. I follow platform guidelines for minimum touch target sizes and test basic screen reader functionality to ensure users can navigate through the app. I try to maintain good color contrast and support dynamic text sizes by using the platform's text scaling features. When implementing custom controls, I add the appropriate accessibility traits or roles so they behave correctly with assistive technologies."

Poor Response: "I add accessibility labels to images and buttons that don't have text. I make sure the app can be used with larger text sizes by testing it with the system font size increased. If QA or users report specific accessibility issues, I fix them as they come up. I generally focus on making sure the core functionality works for all users and add accessibility enhancements when we have time or when specific requirements come from the product team."

16. Describe your approach to implementing networking and API integration in mobile apps.

Great Response: "I implement networking using a layered architecture that separates concerns. At the lowest level, I use a protocol-based network client with configuration for headers, authentication, and request/response interception. Above that, I implement API services that handle endpoint-specific logic, with strong typing for requests and responses. I build a repository layer that abstracts data sources and handles caching strategies. For performance, I implement connection pooling, request prioritization, and cancelable requests. I design comprehensive error handling with typed errors and recovery strategies, including retry with exponential backoff for transient failures. I implement proper caching using HTTP cache headers and local persistence with TTL. To support testing, I use protocols/interfaces for dependency injection and provide mock implementations. I also implement network monitoring to adapt behavior based on connection quality and build analytics to track API performance metrics like error rates and response times."

Mediocre Response: "I typically use libraries like Retrofit or Alamofire to handle API requests, setting up endpoints as services. I create model classes that match the API responses and use serialization libraries like Gson or Codable to parse JSON. I implement error handling for common cases like network failures or server errors, showing appropriate messages to users. For caching, I store responses locally and serve them when offline. I handle authentication by intercepting requests to add tokens and implementing token refresh when needed."

Poor Response: "I use the platform's built-in networking capabilities like URLSession or HttpURLConnection, or sometimes higher-level libraries to simplify things. I create functions to call each API endpoint we need and parse the JSON responses into objects. I add basic error handling to show users when something goes wrong with the network. I focus on getting the data from the server to the UI as efficiently as possible and handle any special cases like authentication as needed."

17. How do you manage state in complex mobile applications?

Great Response: "I implement a unidirectional data flow architecture with a central state store, similar to Redux or MVI (Model-View-Intent). I structure state as immutable objects with explicit transitions through reducers or similar pure functions. For complex apps, I segment state into feature-specific modules with clear interfaces between them. I carefully distinguish between UI state, application state, and domain state, handling each appropriately. For persistence, I implement state restoration across app launches using a combination of saved instance state and longer-term storage. I use reactive programming (RxJava/Combine/Flows) to bind state changes to UI updates with proper threading models. To manage side effects, I implement middleware or dedicated effect handlers that keep side effects isolated from state transitions. For debugging, I add comprehensive state logging and time-travel debugging in development builds. I also implement analytics tracking at the state transition level to understand user behavior patterns."

Mediocre Response: "I use a combination of state management patterns depending on the complexity. For simpler screens, I follow MVVM with LiveData or StateFlow to bind UI elements to viewmodel state. For more complex features, I implement a unidirectional flow using something like Redux patterns. I try to keep state immutable when possible and define clear actions that trigger state changes. I organize state by feature module and use dependency injection to share common state between components when needed."

Poor Response: "I typically store state in the view models or controllers and pass data between screens as needed. For global state like user preferences or session information, I use singletons or a shared service class that components can access. I use events or callbacks to notify different parts of the app when important state changes occur. I try to keep the state management simple and focused on what each screen needs rather than creating complex architectures."

18. What is your experience with implementing analytics and monitoring in mobile apps?

Great Response: "I implement a comprehensive analytics strategy starting with a structured event taxonomy that maps to the user journey. I create an abstraction layer above specific analytics providers that centralizes event definitions and validation while allowing multiple analytics destinations. I instrument critical user flows with funnel events to track conversion and drop-off points, and implement automatic timing for key operations to measure performance in production. For data quality, I validate all events through automated tests and schema validation before deployment. I set up real-time monitoring with alerting for crashes, ANRs, and performance degradation using services like Firebase Performance Monitoring or custom solutions. I implement proper user opt-in/opt-out controls with data minimization principles and anonymize sensitive data. I also create developer dashboards showing key metrics and trends to inform feature development and bug prioritization. For critical issues, I implement breadcrumb collection and enhanced logging that can be remotely enabled for specific users."

Mediocre Response: "I integrate analytics SDKs like Firebase Analytics or Mixpanel and work with product managers to define what events we need to track. I implement event tracking for key user actions and screen views, adding relevant parameters to provide context. I set up crash reporting to identify issues in production. I make sure to respect user privacy by anonymizing data where appropriate and following platform guidelines for tracking consent. I periodically review analytics dashboards to understand how users are using the features I build."

Poor Response: "I add analytics calls to track screen views and important button clicks using whatever analytics solution the project has set up. I make sure to add tracking for new features I build so we can see if users are finding them. I implement crash reporting tools to know when the app is crashing in production. I typically follow the patterns that already exist in the codebase for analytics and add events as requested by the product team."

19. How do you optimize battery usage in mobile applications?

Great Response: "I approach battery optimization systematically, starting with measurement using platform tools like Xcode Energy Gauges or Battery Historian to establish baselines. I implement efficient background processing by batching operations, using proper background modes with constraints, and leveraging platform JobScheduler/WorkManager APIs with appropriate backoff policies. For networking, I implement intelligent polling with adaptive intervals, efficient data transfer with compressed payloads, and connection pooling to minimize radio activation. I optimize location services using significant change location updates instead of continuous tracking, region monitoring instead of geofencing when appropriate, and dynamic accuracy adjustments based on app state. I minimize wake locks and wakelocks, leveraging platform doze mode compatibility. I also implement power-aware feature adjustments that detect low battery situations and adjust functionality accordingly, like reducing animation complexity or sync frequency. Finally, I set up battery usage monitoring in production builds to identify regressions and optimize continuously."

Mediocre Response: "I focus on minimizing background activity by using efficient background processing APIs like WorkManager or BackgroundTasks. I batch network requests when possible and implement proper caching to reduce unnecessary data transfers. For location tracking, I adjust the accuracy and frequency based on the app's needs at the moment. I make sure to stop any resource-intensive operations when the app goes to the background and properly clean up resources. I test on real devices to identify and fix any operations that might be draining battery unnecessarily."

Poor Response: "I try to follow platform best practices for battery usage. I avoid keeping unnecessary processes running in the background and try to limit how often the app needs to wake up. If users report battery drain issues, I'll investigate what might be causing it and optimize those specific areas. I generally rely on the operating system to manage battery usage efficiently and focus on building features according to requirements."

20. What experience do you have with native module development or bridging to native code?

Great Response: "I've developed comprehensive native modules for both React Native and Flutter applications. I've implemented complex native functionality like custom camera interfaces with real-time processing, hardware-accelerated video effects, and deep integration with platform-specific APIs not exposed through the framework. I design native bridges with clean APIs that hide implementation details while providing type-safe interfaces. I carefully manage memory and threading, ensuring long-running operations don't block the UI thread by implementing proper threading models using GCD/Dispatch Queues on iOS and HandlerThreads on Android. For error handling, I create consistent error mapping between native and cross-platform layers with meaningful error messages. I've also optimized performance-critical paths by moving processing to native code, achieving significant performance improvements. For all native modules, I implement proper resource cleanup and lifecycle awareness to prevent memory leaks and crashes. I also maintain comprehensive documentation for both internal team use and open-source contributions."

Mediocre Response: "I've created native modules for React Native apps when we needed functionality not available in existing packages. I've implemented bridges to native device features like custom camera controls and Bluetooth communication. I follow the bridging guidelines for each platform, creating proper method signatures and handling data conversion between JavaScript and native code. I make sure to handle errors properly and provide clear feedback when native operations fail. I've also worked with existing native libraries by creating wrapper modules that expose their functionality to the cross-platform layer."

Poor Response: "I've used existing native modules in cross-platform apps and made minor modifications to them when needed. When we've required native functionality, I usually look for existing packages first. If nothing exists, I'll create basic native modules following the examples in the documentation. I focus mostly on getting the functionality working correctly and rely on the framework's built-in tools to handle the communication between native and cross-platform code. For complex native features, I typically consult with more experienced native developers on the team."