Interview questions in Mobile Dev, page 18
Designing a native map UI component
Wrap each platform's native view, expose props mapped to native setters and events as bubbling callbacks, unify behind one JS API.
URLSession data vs download vs upload tasks
Data tasks buffer responses in memory for small API calls; download tasks stream to a file and support background transfers for large files; upload tasks send bodies from data or files and report…
How do you manage product list and favorite state without full rebuilds?
This tests granular rebuild control in Flutter lists. A strong answer isolates item state with ValueNotifier or ChangeNotifier per item plus const constructors with keys. Red flag: calling setState on the parent list rebuilds every ListTile on each tap.
Explain the purpose of a UseCase and how it fits into MVVM
UseCases encapsulate single business rules between ViewModel and Repository, keeping ViewModels lean and Repositories focused on data.
Explain the purpose of a UseCase or Interactor layer
Tests your grasp of separation of concerns. A great answer defines a UseCase as a single, reusable business operation that sits between the ViewModel and Repository. It keeps other layers clean and focused.
Responsive layout across form factors
Drive layout from dimensions and breakpoints via useWindowDimensions, react to orientation changes, avoid hardcoded OS checks.
Run two API calls concurrently with async let
Use async let to start two independent fetches that run concurrently, then await both, so total time approaches the slower call rather than the sum.
Explain lifting state up in Flutter and how Provider simplifies it
Tests declarative state ownership and prop-drilling cost. A strong answer names the lowest common ancestor, contrasts callback threading with Provider lookup, and avoids root-level state.
How would you architect two source Flows from ViewModel to data layer?
This tests merging parallel async streams into one reactive state. A strong answer uses combine on two cold repository Flows, exposes one UI state Flow from the ViewModel, and maps failures to error states. Red flag: using two coroutines mutating shared state.
Combine two network sources using Coroutines and Flow
Tests your grasp of async data combination and state management. A good answer uses Flow.combine in a ViewModel, fed by a Repository, emitting a sealed class for UI state (Loading, Success, Error). A red flag is trying to combine state in the UI layer itself.
useNativeDriver in the Animated API
Native driver runs animations on the UI thread so they stay smooth even if JS is busy, but only supports non-layout props like transform and opacity.
What is @MainActor and why does it matter?
@MainActor is a global actor guaranteeing code runs on the main thread; annotate UI-updating types or methods so post-network state changes are main-thread safe.
Immutable bloc state versus mutable ChangeNotifier
Immutable gives predictable diffs, easy debugging and replayability at the cost of boilerplate; mutable is terse but error-prone.
How do you navigate between feature modules without direct dependencies?
This tests architectural decoupling in multi-module Android apps. A great answer describes a shared navigation contract or deep-link router that lets features stay independent. Recommending direct Gradle dependencies between features is a major red flag.
Navigate between feature modules without direct dependencies?
Tests dependency inversion in modular apps. Answer by defining navigation interfaces in a shared module, implementing them in the :app module, and using DI to connect them. A red flag is suggesting direct module dependencies or using reflection for navigation.
Build a mount fade-in with Animated API
Create an Animated.Value(0) in a ref, drive it with Animated.timing inside useEffect, bind it to opacity on Animated.View.
Add a default header to every URLSession request
Set httpAdditionalHeaders on a URLSessionConfiguration, build the session from it, mention per-request overrides win.
Make a GET request with http and parse JSON in Dart
Practical Dart async networking with package:http and dart:convert. Import http, await get(Uri.parse(url)), verify statusCode is 200, then jsonDecode(response.body) as List<Map<String, dynamic>>. Skipping status checks or decoding without a cast.
How would you architect state-driven UI with ViewModel and Compose?
Tests unidirectional data flow and state hoisting. Model screen state as an immutable data class, expose StateFlow from ViewModel, and collect it in Compose so events flow up and state down. Red flag: exposing mutable state or putting logic in Composables.
Animated.sequence versus Animated.parallel
Sequence runs animations one after another in order, parallel starts them at the same time.
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