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Mobile App Development Telephonic Interview Questions & Answers

30 questions for the telephonic interview stage — 17 easy, 13 medium.

About the telephonic interview round

The telephonic or screening round is a 15-30 minute call with a recruiter or engineer. It checks your basics, your CV and whether you can explain Mobile App Development concepts clearly without a screen to point at.

Tips for the telephonic interview round

  • Keep your CV in front of you and be ready to explain every line on it.
  • Answer in short, clear sentences; there is no whiteboard, so structure matters.
  • Take the call somewhere quiet and confirm the time in advance.
  • Prepare one question to ask the interviewer at the end.
Solved — telephonic interviewStart practicing
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01

How does token-based authentication work in mobile apps?

Mobile Backend, APIs and FirebaseMedium
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The user signs in and the server returns a short-lived access token, often a JWT, and a longer-lived refresh token. The app stores them securely in Keychain or Keystore-backed storage and sends the access token in the Authorization header. When it expires, the app uses the refresh token to get a new one, retrying the failed request. On logout, tokens are deleted and ideally revoked on the server.
02

What is Maestro and why do mobile teams use it?

Testing, Performance and CI/CDMedium
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Maestro is an open-source mobile UI testing framework where flows are written in simple YAML, such as launchApp, tapOn "Login" and assertVisible "Welcome". It works with native, Flutter and React Native apps on Android and iOS, handles waiting automatically, and reduces flakiness compared to many older tools. Teams use it for smoke tests of critical journeys in CI because tests are quick to write and readable by QA.
03

How does navigation work in React Native with React Navigation?

React Native Navigation, State and Native ModulesEasy
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React Navigation provides navigators: native stack for push and pop screens using platform transitions, bottom tabs, drawer and material top tabs. You nest navigators, for example tabs inside a root stack with modal screens. Screens receive navigation and route props or use hooks like useNavigation and useRoute. Version 7 adds a static configuration API for better TypeScript inference and automatic deep link setup.
04

What are useMemo, useCallback and React.memo used for?

React Native CoreMedium
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React.memo skips re-rendering a component when its props are shallowly equal. useCallback keeps the same function reference between renders, and useMemo caches a computed value, both only changing when dependencies change. They help when passing callbacks to memoised list items or computing expensive values. Overusing them adds complexity with little gain; the React Compiler can now apply such memoisation automatically in supported projects.
05

Tell me about a time you worked with a backend developer to fix an integration issue.

Mobile Backend, APIs and FirebaseEasy
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Situation: our app showed wrong prices after a discount launch. Task: find whether the app or API was at fault. Action: I captured the failing request and response with a proxy, shared it with the backend developer, and we found the API returned paise in one endpoint and rupees in another. We agreed on one format, updated the contract document and added a test. Result: the bug was fixed the same day.
06

Explain the core React Native components.

React Native CoreEasy
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View is the basic container, like a div, supporting flexbox layout and styles. Text displays text, and all strings must be inside Text. Image shows images from network or local sources. TextInput handles keyboard input. Pressable handles touches with press states. ScrollView scrolls a small amount of content, while FlatList and SectionList render long lists virtually. SafeAreaView or the safe area context library keeps content away from notches.
07

What is the difference between ScrollView and FlatList?

React Native CoreEasy
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ScrollView renders all its children at once, which is fine for short content but uses lots of memory and slows rendering for long lists. FlatList virtualises, rendering only items near the viewport and recycling as you scroll, with props like keyExtractor, initialNumToRender and windowSize. For very large or complex lists, FlashList offers better recycling and performance. Never nest a FlatList inside a ScrollView of the same direction.
08

What types of tests do you write in Flutter?

Testing, Performance and CI/CDEasy
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Unit tests check pure Dart logic like validators, repositories and state notifiers. Widget tests render a single widget or screen in a test environment with WidgetTester, simulate taps and text entry, and assert what appears, running fast without a device. Integration tests, using the integration_test package, run the full app on a device or emulator for end-to-end flows. Golden tests compare widget screenshots to catch visual regressions.
09

What is responsive design in mobile apps and how do you handle different screen sizes?

Mobile Development FundamentalsMedium
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Responsive design means layouts adapt to screen width, orientation, foldables and tablets instead of using fixed sizes. Use flexible layouts, percentages or flex, and breakpoints for compact, medium and expanded widths. In Flutter use LayoutBuilder and MediaQuery.sizeOf; in React Native use flexbox and useWindowDimensions. Respect safe areas for notches and system bars, support text scaling for accessibility, and test on small budget phones.
10

How do you make sure your code works before handing it to QA?

Testing, Performance and CI/CDEasy
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I test the happy path and edge cases myself on both Android and iOS, including no network, slow network, empty states, large text sizes and rotation. I write unit tests for logic and run the existing test suite. I review my own diff before raising the pull request and add clear testing notes for QA explaining what changed and what to check, which saves time for both of us.
11

What local storage options exist for Flutter and React Native apps?

Mobile Backend, APIs and FirebaseEasy
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For simple key-value settings, Flutter uses shared_preferences and React Native uses AsyncStorage or MMKV. For sensitive data, flutter_secure_storage or expo-secure-store use Keychain and Keystore. For structured data and queries, use SQLite via sqflite or drift in Flutter and expo-sqlite or WatermelonDB in React Native. Object stores like Isar, Hive or Realm also exist, but check maintenance status before choosing.
12

What is a Stream in Dart and how is it used in Flutter?

Dart and Flutter BasicsMedium
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A Stream delivers a sequence of asynchronous events, such as real-time database updates, location changes or WebSocket messages. You listen with listen() or await for, and transform with map, where and debounce from packages. Single-subscription streams allow one listener; broadcast streams allow many. In Flutter, StreamBuilder rebuilds UI on each event. Always cancel subscriptions in dispose to prevent leaks.
13

How do you handle pressure when a production issue affects many users?

Mobile Backend, APIs and FirebaseMedium
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I stay calm and focus on reducing impact first: confirm the issue, communicate status to the team, and look for the fastest safe mitigation such as a remote config switch, server-side fix or pausing a rollout. Then I find the root cause, ship a proper fix and write a short postmortem. Clear, regular updates to stakeholders reduce panic and let others plan around the issue.
14

How do you pass parameters between screens and type them safely?

React Native Navigation, State and Native ModulesEasy
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Pass small, serialisable params like IDs with navigation.navigate('Details', { id }), and read them with route.params. Define a param list type, such as type RootStackParamList = { Details: { id: string } }, and use it with the navigator and hooks for type checking. Avoid passing functions or large objects, which break state persistence and deep linking; fetch full data on the destination screen.
15

How does Flutter render UI differently from React Native?

Mobile Development FundamentalsMedium
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Flutter draws every pixel itself using its own rendering engine, Impeller, onto a canvas, so widgets look identical across platforms and do not depend on native UI components. React Native maps components like View and Text to real native views, so the UI uses platform controls. Flutter gives pixel consistency and predictable performance; React Native gives native look and easier reuse of native view libraries, plus web developer familiarity with JavaScript.
16

Integration tests pass locally but fail randomly in CI. How do you make them reliable?

Testing, Performance and CI/CDMedium
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Flaky tests usually come from timing assumptions, shared state, network dependence or slow emulators. Replace fixed delays with waiting for specific conditions, mock or stub network calls with predictable responses, reset app data between tests, and use stable selectors like keys or test IDs instead of text that changes. Give CI emulators enough resources, retry only as a temporary measure, and track flaky tests separately to fix them.
17

What is the difference between native, cross-platform and hybrid mobile apps?

Mobile Development FundamentalsEasy
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Native apps are written in platform languages, Kotlin for Android and Swift for iOS, with full access to platform APIs and the best performance. Cross-platform frameworks like Flutter and React Native share one codebase and render native-feeling UI, saving time for two platforms. Hybrid apps, such as Ionic or Cordova, run web code inside a WebView. Choice depends on performance needs, team skills, budget and how much platform-specific UI is required.
18

What is Firebase and which services do mobile apps commonly use?

Mobile Backend, APIs and FirebaseEasy
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Firebase is a mobile and web development platform. Commonly used services are Authentication for email, phone OTP and social logins; Cloud Firestore and Realtime Database for synced data; Cloud Storage for files; Cloud Functions for server code; Cloud Messaging for push notifications; Crashlytics for crash reports; Analytics; Remote Config for feature flags; and App Distribution for testers. FlutterFire and React Native Firebase provide SDKs.
19

What are runtime permissions and how do they differ between platforms?

Mobile Development FundamentalsMedium
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Both platforms require runtime approval for sensitive features like camera, location, contacts and notifications. Android requires declarations in AndroidManifest.xml and runtime requests for dangerous permissions; iOS requires usage description strings in Info.plist, and the app crashes if a description is missing when requesting. iOS allows asking only once; later the user must change settings. Plugins like permission_handler or react-native-permissions unify the API.
20

Why do Flutter apps need a state management solution beyond setState?

Flutter State Management and ArchitectureEasy
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setState works for local UI state inside one widget, but shared state like the logged-in user, cart or settings must be read and changed by many screens. Passing it through constructors becomes messy, and rebuilding large trees hurts performance. State management libraries separate business logic from UI, make state testable, rebuild only widgets that depend on changed data, and give a clear, predictable flow of updates.
21

How do push notifications work end to end?

Mobile Backend, APIs and FirebaseMedium
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The app registers with the platform push service, FCM on Android and APNs on iOS, often both through FCM, and receives a device token. The app sends this token to your backend, linked to the user. When an event happens, the backend sends a message to FCM or APNs with the token, which delivers it to the device. The app requests notification permission, handles taps to open the right screen, and refreshes tokens when they change.
22

Your app works on Android but crashes immediately on iOS when the user taps the camera button. What is the likely cause?

Mobile Development FundamentalsEasy
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The most common cause is a missing NSCameraUsageDescription key in Info.plist. iOS terminates the app when it requests a protected resource without a usage description string. Add descriptions for camera, photo library, microphone and location as required by the plugin, written clearly for the user. Also verify the plugin's iOS setup steps, run pod install, and test on a real device since simulators lack cameras.
23

How do you test React Native components?

Testing, Performance and CI/CDEasy
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Use Jest as the test runner with React Native Testing Library, which renders components and queries them the way users do, by text, role or label. Fire events like fireEvent.press or userEvent, then assert on output. Mock native modules and network calls with jest mocks or MSW. For end-to-end tests on real builds, use Detox or Maestro, which drive the app on emulators and simulators.
24

What is accessibility in mobile apps and how do you implement it?

Mobile Development FundamentalsMedium
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Accessibility makes apps usable by people with disabilities. Provide labels for icons and images so screen readers like TalkBack and VoiceOver can announce them, keep touch targets at least 44 to 48 points, support dynamic text sizes, ensure colour contrast, and avoid conveying information only by colour. Flutter uses Semantics widgets, and React Native uses accessibilityLabel and accessibilityRole. Test with screen readers enabled.
25

What are the steps to publish an iOS app on the App Store?

App Store and Play Store PublishingEasy
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Enrol in the developer program, create an App ID and the app record in App Store Connect, and set up signing with certificates and provisioning profiles, often managed automatically by Xcode or EAS. Archive the release build with an incremented build number, upload it, and test through TestFlight. Complete metadata, screenshots, privacy nutrition labels and age rating, then submit for review. After approval, release manually, automatically or in phased release.
26

What are versionName, versionCode and build numbers?

App Store and Play Store PublishingEasy
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On Android, versionName is the user-visible version like 2.3.1 and versionCode is an integer that must increase with every upload. On iOS, CFBundleShortVersionString is the marketing version and CFBundleVersion is the build number, which must be unique per version upload. In Flutter, the pubspec version 2.3.1+45 sets both; in Expo, version and the platform build numbers are set in app config and can auto-increment with EAS.
27

What is App Store Optimisation and what can a developer influence?

App Store and Play Store PublishingMedium
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App Store Optimisation improves an app's visibility and conversion in store search. Key factors are the app title, subtitle or short description, keywords, long description, screenshots, preview videos, ratings and reviews. Developers influence it by keeping app size small, crash rates low and performance high, since store algorithms consider quality signals, by adding in-app review prompts at good moments, and by supporting localisation for regional languages.
28

What is the difference between final and const in Dart?

Dart and Flutter BasicsEasy
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final means a variable is assigned once at runtime and cannot be reassigned. const means the value is a compile-time constant and deeply immutable. In Flutter, const constructors like const Text("Hello") let the framework reuse the same widget instance across rebuilds, skipping unnecessary work. Use const wherever possible for widgets with fixed values; the linter rule prefer_const_constructors helps enforce it.
29

What is the freezed package used for?

Flutter State Management and ArchitectureMedium
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freezed generates immutable data classes with copyWith, equality, toString and union types or sealed classes, and integrates with json_serializable for fromJson and toJson. It removes boilerplate when modelling state such as loading, data and error variants. You annotate a class, run build_runner, and get generated code in a part file. With Dart 3 sealed classes and records, some teams need it less, but it is still widely used.
30

Tell me about an app you published and what you learned from real users.

App Store and Play Store PublishingEasy
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Situation: I published a notes app with a friend and got about 2,000 installs. Task: improve ratings stuck at 3.6. Action: I read every review, found users disliked losing notes when switching phones, added cloud backup and a clear onboarding screen, and fixed two crashes from Crashlytics. Result: rating rose to 4.4 in two months. I learned to prioritise what users actually complain about over features I assumed they wanted.

Frequently asked questions

What happens in the Mobile App Development telephonic interview round?

The telephonic or screening round is a 15-30 minute call with a recruiter or engineer. It checks your basics, your CV and whether you can explain Mobile App Development concepts clearly without a screen to point at.

How do I clear the telephonic interview round?

Keep your CV in front of you and be ready to explain every line on it. Answer in short, clear sentences; there is no whiteboard, so structure matters. Take the call somewhere quiet and confirm the time in advance.

Which round comes next?

A typical order is online assessment, telephonic screening, one or two technical rounds, a managerial round and HR. Use the other round pages to practise each stage.

Practise every interview round

Online Assessment questionsTechnical Round questionsManagerial Round questionsRapid-Fire questionsHR & behavioural questionsFull mock interview

More ways to practise

Company-wise Mobile App Development questionsExperience-wise Mobile App Development questionsRole-wise Mobile App Development questionsCity-wise Mobile App Development questionsMost asked Mobile App Development questionsScenario-based questionsPractical / hands-on questionsHR & behavioural questionsMobile App Development mock interviewOnline assessment questionsTechnical round questionsManagerial round questionsMobile App Development topic sheets