Interview questions in Mobile Dev, page 8
What is the build method's purpose and key constraints?
It returns a Widget tree, can run every frame, must avoid side effects, and uses BuildContext for inherited data.
App crash: debug with Logcat and breakpoints in Android Studio
This tests systematic debugging and Android Studio fluency. A strong answer reproduces the crash, filters Logcat for the fatal exception, sets a breakpoint on the offending frame, and inspects variables.
How would you debug an app crash in Android Studio?
This tests your systematic debugging process. A good answer starts with Logcat to find the stack trace, then uses breakpoints to inspect program state *before* the crash occurs. A red flag is randomly adding print statements instead of using the debugger.
How do you debug an app crash in Android Studio?
Tests your systematic problem-solving process. A great answer outlines reproducing the crash, analyzing the Logcat stack trace for the FATAL EXCEPTION, and then using strategic breakpoints and the variable inspector to find the root cause of the bad state.
Configuring deep linking to a parameterized screen
Register native URL schemes/intent filters, define a linking config with prefixes and screen-to-path mapping including params, pass it to NavigationContainer.
How do UITableView and UICollectionView reuse cells?
This tests your understanding of UIKit's flyweight pattern and scroll performance. A strong answer covers the reuse pool, dequeueReusableCell mapping identifiers to new index paths, and registration.
Relationship between Widget, Element, and RenderObject trees and their benefits
Widget configures, Element owns state, RenderObject paints; Element.update reuses the RenderObject, so rebuilds stay cheap.
Explain what a Gradle product flavor is and give a free vs pro example
Tests understanding of build-variant dimensions beyond build types. A strong answer defines flavorDimensions, sets free and pro applicationIdSuffix values, and explains variant generation. Red flag: conflating flavors with build types or manual APK renaming.
What is a Gradle product flavor?
This tests your understanding of build variants beyond debug/release. Define flavors for user-facing versions (free/pro), contrast with build types, and configure with applicationIdSuffix and buildConfigField.
Explain Gradle product flavors with a free/pro app example
This tests your grasp of the build variant matrix, not just flavors. A great answer defines flavors, explains how they combine with build types, details Gradle config (applicationIdSuffix), and mentions source sets.
How react-native-screens optimizes a deep stack
React-native-screens uses native container views so off-screen screens are detached from the view hierarchy and can be freed; enabled by default and powers the native-stack navigator.
Compare UIKit Auto Layout and SwiftUI layout systems
Tests imperative versus declarative layout paradigms. Contrast UIKit's constraint solver with SwiftUI's two-pass sizing and composition via stacks and modifiers instead of anchors. Red flag: claiming SwiftUI uses Auto Layout under the hood.
What is BuildContext? Give two tree-interaction examples.
Tests if you know BuildContext is an Element handle to a widget's tree location. Strong answers cite Theme.of and Scaffold.of as ancestor lookups, explain the own-context trap, and warn against caching across async gaps. Red flag: calling it the widget itself.
Which Android Studio tool inspects view hierarchy and what does it show?
Tests practical knowledge of runtime UI debugging tools. A strong answer names Layout Inspector, cites live view hierarchy with bounds and attributes, and distinguishes it from the static Layout Editor. Red flag: citing Logcat or the preview pane instead.
Which tool inspects the view hierarchy to debug layouts?
This tests your knowledge of core Android Studio debugging tools. A great answer names the Layout Inspector, describes its 3D component tree and attributes pane, and notes its live update capability on API 29+. A red flag is only mentioning XML files.
How do you debug a running app's view hierarchy?
Tests practical debugging skills. A good answer names the Layout Inspector, describes the component tree and attributes panes, and explains how the 3D view finds hidden elements. A red flag is only naming the tool without explaining its use.
Type-safe navigation with TypeScript
Define a ParamList mapping screen names to param types, type Screen via NativeStackScreenProps, and type useNavigation with the navigation prop generic so route names and params autocomplete.
Differences between @State, @Binding, @ObservedObject, and @EnvironmentObject
Tests SwiftUI state ownership and propagation. @State owns local value types; @Binding borrows for two-way edits; @ObservedObject accepts an external ObservableObject; @EnvironmentObject reads one from the environment.
How can you prevent unnecessary child rebuilds in Flutter?
Tests your grasp of Flutter build-boundary isolation. Strong answers hit const constructors, extracting the child into its own widget, and granular state selectors. Red flag: saying Keys alone stop rebuilds or recommending RepaintBoundary to skip builds.
What is ADB? Describe two common commands and what they accomplish.
This tests command-line debugging fluency. Define ADB as a client-server bridge, then give two commands such as adb install for APK deployment and adb logcat for streaming device logs. Red flag: calling it the Android Studio debugger or omitting the daemon.
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