Easy interview questions in Mobile Dev, page 8
App ID, provisioning profile, and signing certificate
The certificate proves who you are, the App ID identifies the app and its capabilities, and the provisioning profile binds certificate, App ID, and allowed devices so iOS trusts the install.
Archiving and uploading a build to TestFlight
Select a real-device or Any iOS destination, Product Archive, then in the Organizer distribute to App Store Connect, where the build appears for internal TestFlight testers after processing.
Unit, widget, and integration test differences in Flutter
Tests your grasp of Flutter's test pyramid and isolation levels. Unit tests check pure Dart logic; widget tests verify UI in a headless environment; integration tests exercise the full app on a device. Red flag: saying widget tests require an emulator.
Unit testing vs component testing in React Native
Unit tests verify isolated functions/logic with Jest; component tests render components and assert behavior with React Native Testing Library.
How do you verify a Text widget with 'Hello' is present?
Find.text('Hello') locates the widget; expect(finder, findsOneWidget) asserts exactly one exists.
Flutter command for an Android release build and APK vs AAB difference.
Flutter CLI release commands and Android distribution formats. Name flutter build apk and flutter build appbundle; note AAB lets Google Play generate optimized APKs per device while APK is a single direct-install file.
What is an Android memory leak? Give a Context example and fix.
Tests understanding of Activity Context retention preventing GC. A strong answer defines a leak as unreachable objects, gives a static singleton example, names LeakCanary, and fixes it with Application Context. Red flag: blaming GC or suggesting System.gc().
How would you manage different backend environments in a Flutter project?
Tests Flutter build flavors and compile-time config injection. A strong answer uses dart-define or flavor-specific entry points plus an EnvironmentConfig abstraction. A red flag is manually swapping hard-coded base URLs before each build.
What is overdraw in Android UI and how do you reduce it?
This tests GPU fill awareness. A strong answer defines overdraw as redrawing pixels repeatedly, names Debug GPU Overdraw's color overlay, and offers fixes: remove unnecessary backgrounds and flatten hierarchies. Red flag: confusing this with CPU layout issues.
iOS Provisioning Profiles and Signing Certificates
The certificate proves developer identity, the App ID names the app, the profile binds certificate, App ID, and devices.
Purpose and setup of an Objective-C bridging header
The bridging header imports ObjC headers into Swift; Xcode auto-creates it or you add it manually and set the build setting.
Why avoid plain SharedPreferences for secrets and what to use?
Tests data-at-rest security awareness. A strong answer notes plain SharedPreferences writes unencrypted XML that rooted users or backups expose, then names EncryptedSharedPreferences with Android Keystore.
Managing Per-Environment Configuration in React Native
Use per-environment env files plus build flavors or schemes, inject at build time, keep secrets off the device.
Diagnosing choppy scrolling performance
Reach for Instruments, especially the Time Profiler and Core Animation/Hangs tools, and look for main-thread work and dropped frames.
Why use const for Flutter widgets and how does it improve performance?
Tests widget canonicalization and rebuild short-circuiting. Strong answer: const enables instance reuse and skips subtree rebuilds on parent updates, reducing allocations.
Flutter's Widget, Element, and RenderObject trees: roles and relationships
Tests your mental model of Flutter's rendering layers. Strong answer: Widget is immutable configuration; Element is the mutable lifecycle manager owning the RenderObject; RenderObject is the concrete layout and paint entity.
Purpose of Android app signing and keystore contents
Signing proves authorship and integrity, enables same-key updates, and binds app identity; a keystore holds private keys and certificates.
What is an Android App Bundle and its advantages over APK?
Tests knowledge of modern Play distribution. AAB is the publishing format with all code and resources; Play generates device-specific APKs for smaller downloads and supports dynamic features. Red flag: calling it a compressed APK or ignoring dynamic delivery.
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