Mobile app development is a fast-growing field focused on creating applications for smartphones and tablets across platforms like iOS and Android. Interviewers test candidates on programming languages, mobile frameworks, UI/UX principles, performance optimization, and platform-specific knowledge. The following 25 Mobile App Developer Interview Questions and Answers will help you prepare effectively.
Q1. What are the main platforms for mobile app development?
The primary platforms are Android and iOS.
Q2. What programming languages are commonly used for mobile app development?
Java and Kotlin for Android; Swift and Objective-C for iOS; JavaScript/TypeScript for cross-platform frameworks like React Native and Flutter (Dart).
Q3. What is the difference between native, hybrid, and cross-platform mobile apps?
Native apps are built specifically for one platform using platform-specific languages. Hybrid apps use web technologies inside a native container. Cross-platform apps use frameworks to build one codebase for multiple platforms.
Q4. What is Android SDK?
Android Software Development Kit (SDK) provides tools, libraries, and APIs to develop Android apps.
Q5. What is an Activity in Android?
An Activity represents a single screen with a user interface in an Android app.
Q6. What is an Intent in Android?
Intent is a messaging object used to request an action from another app component, such as starting an Activity or service.
Q7. Explain the lifecycle of an Android Activity.
Key lifecycle methods include onCreate, onStart, onResume, onPause, onStop, onDestroy, and onRestart, managing the state transitions of an Activity.
Q8. What is a Fragment in Android?
A Fragment represents a reusable portion of UI within an Activity, enabling modular UI design.
Q9. What are the advantages of using Kotlin for Android development?
Kotlin offers concise syntax, null safety, interoperability with Java, coroutines for async programming, and is officially supported by Google.
Q10. What is Swift and why is it preferred for iOS development?
Swift is a modern, fast, and safe programming language developed by Apple for iOS and macOS apps.
Q11. What is the difference between UIViewController and AppDelegate in iOS?
UIViewController manages a screen’s UI, while AppDelegate handles app-level events like launch, backgrounding, and notifications.
Q12. What is the purpose of Storyboards in iOS development?
Storyboards visually design UI screens and define transitions (segues) between them.
Q13. What is memory management in mobile apps?
Managing memory involves allocating, using, and freeing resources efficiently to avoid leaks and crashes.
Q14. What are background services in Android?
Background services perform operations without a user interface, such as downloading data or syncing in the background.
Q15. How do you handle offline functionality in mobile apps?
By caching data locally using databases (e.g., SQLite, Realm) or storage APIs and syncing with the server when online.
Q16. What is React Native?
React Native is a cross-platform framework that allows building mobile apps using JavaScript and React.
Q17. What are some ways to optimize mobile app performance?
Minimize memory use, optimize images, reduce network calls, use efficient algorithms, and perform tasks asynchronously.
Q18. How do push notifications work in mobile apps?
Push notifications are messages sent from a server to the device, delivered via platform services like Firebase Cloud Messaging or Apple Push Notification Service.
Q19. What is the difference between AsyncTask and Thread in Android?
AsyncTask is a helper class for short background operations with UI thread callbacks, while Thread is a basic concurrency tool.
Q20. How do you ensure app security on mobile devices?
Use secure data storage, encrypt data transmission, implement authentication, avoid sensitive data exposure, and use platform security features.
Q21. What is Flutter?
Flutter is a UI toolkit by Google for building natively compiled cross-platform apps using the Dart language.
Q22. What are platform-specific considerations when developing mobile apps?
Differences in UI guidelines, hardware capabilities, OS behaviors, app store policies, and lifecycle management.
Q23. How do you test mobile applications?
Using unit tests, UI tests, automated testing tools, emulators/simulators, and real device testing.
Q24. What is the Google Play Store and Apple App Store submission process?
It involves app packaging, signing, uploading, review, and compliance with store guidelines before publishing.
Q25. What is the importance of responsive design in mobile apps?
Responsive design ensures the app looks and works well on various screen sizes and orientations.