Intermediate interview questions in Mobile Dev, page 8
How to use a nested navigation graph for a login flow?
Tests your ability to structure complex UI flows using Navigation Component. A great answer defines a separate login graph XML, includes it in the main graph, and navigates to the graph's ID. This encapsulates the flow, making it reusable.
Conditional logic with Platform.Version
Platform.Version is a number on Android (API level) and a string on iOS; gate features by version to use new APIs only where supported.
Difference between context.watch, context.read, and Selector in Provider and Riverpod
Tests rebuild granularity in Flutter. A strong answer distinguishes listening versus one-time lookup, explains that Selector filters rebuilds by comparing sub-values, and warns that context.read inside build causes missed updates.
How do you share a ViewModel across multiple Fragments?
Tests ViewModel scoping and Fragment communication. A strong answer names activityViewModels or navGraphViewModels, warns about Activity memory retention and hidden coupling, and suggests a parent Fragment or data flow alternative.
How do you share a ViewModel between Fragments?
Tests your understanding of ViewModel lifecycle scoping beyond a single screen. To share, scope the ViewModel to the parent Activity or a navigation graph using activityViewModels() or navGraphViewModels().
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.
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.
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.
Add a default header to every URLSession request
Set httpAdditionalHeaders on a URLSessionConfiguration, build the session from it, mention per-request overrides win.
Animated.sequence versus Animated.parallel
Sequence runs animations one after another in order, parallel starts them at the same time.
Animated API versus Reanimated architecture
Animated declares animations that the native driver runs, but logic and gestures cross the bridge; Reanimated runs worklets directly on the UI thread.
Shared values and useAnimatedStyle in Reanimated
UseSharedValue holds a mutable .value readable on both threads, useAnimatedStyle derives styles as a worklet, mutate .value with withTiming or withSpring.
Describe a robust error handling strategy for network requests
Tests whether you classify failures by layer rather than catching everything generically. Inspect DioExceptionType for connectivity, check HTTP status before parsing, and isolate JSON decode errors. Never show the same message for timeouts and 500s.
Animated.event for scroll-driven parallax
Animated.event maps an event path to an Animated.Value, wire it to onScroll with useNativeDriver, then interpolate the value for header transform.
Compare manual JSON serialization versus json_serializable
It tests build automation versus manual control in Dart serialization. Manual methods avoid build steps but risk drift; code generation cuts boilerplate but adds compile latency. Claiming code gen slows runtime or that manual is always simpler.
How do you add a non-null column with a default in Room?
Bump version; run ALTER TABLE ADD COLUMN with NOT NULL DEFAULT in a Migration; register via addMigrations.
We are hiring for this. Every open role lists the topics its interview covers, so you can prepare for the real thing rather than guessing.
See open roles