Interview questions in Mobile Dev, page 16
Optimistic UI updates for actions
Update UI immediately on the assumption of success, send the request, then confirm or roll back on failure.
Describe a pattern for background Core Data fetches and UI updates
This tests NSManagedObjectContext concurrency and queue confinement. Strong answer: create a background context, fetch, pass objectIDs or structs to main, then main context fetches by ID to update UI. Red flag: passing NSManagedObjects across threads.
Explain the core responsibilities of RouterDelegate, RouteInformationParser, and Router in Flutter
Tests Navigator 2.0 architecture split. RouteInformationParser converts URLs to typed config; RouterDelegate owns state and builds the Navigator; Router wires them together and handles engine intents. Red flag: conflating parsing and state or omitting Router.
Diagnose Compose recomposition issues and explain lambda stability
Tests Compose skipping and stability. Strong answers name recomposition counts, compiler metrics, and immutable state, then explain unremembered lambdas create new instances and prevent skipping.
How do you diagnose and fix excessive recomposition in Jetpack Compose?
This tests your grasp of Compose's stability system. First, use Layout Inspector to find high-recomposition areas. Then, enable and analyze the Compose compiler report to diagnose unstable parameters (like List) or lambdas.
How do you diagnose and fix excessive recomposition in Jetpack Compose?
This tests your understanding of Compose's stability system for performance. Use the Layout Inspector and Compiler Metrics to find unstable composables, then fix them with immutable data types and stable lambdas.
Offline data persistence and mutation queue
Persist reads to local storage, store mutations in a durable queue with client ids and status, drain and reconcile on reconnect via NetInfo.
Describe lightweight vs heavyweight Core Data migration and a heavyweight example
This tests inferred versus manual Core Data migrations. Contrast lightweight additive changes with heavyweight transforms like entity splits, citing promoting a string to a new entity. A red flag is claiming renames always need custom mapping.
Implement a GoRouter path parameter route and access userId in a widget
This tests GoRouter declarative routing and GoRouterState. Define a GoRoute with path '/users/:userId', read state.params['userId'] in the builder, and handle null-safety. A red flag is parsing the URI manually or using ModalRoute.of instead of state.params.
What is a ViewModel and what lifecycle problem does it solve?
Tests config-change survival: ViewModel outlives Activity recreation so state survives rotation. Strong answer notes it holds non-serializable data and separates concerns, but does not survive process death.
What is a Jetpack ViewModel and the problem it solves?
This tests your understanding of lifecycle-aware state preservation. A good answer explains that ViewModels survive configuration changes (like rotation) to hold UI data, separating it from the transient UI controller.
What problem does Jetpack ViewModel solve during configuration changes?
This tests your understanding of state loss during configuration changes. A good answer explains that Activities are destroyed on rotation, and ViewModel survives this event, preserving UI state.
Apollo's normalized cache
Apollo flattens query results into entities keyed by type plus id, so one object is stored once and shared, updating everywhere at once.
Optimize a slow NSFetchedResultsController screen
Set fetchBatchSize so rows load in pages, use relationshipKeyPathsForPrefetching to avoid per-row faulting round trips, and add indexes matching sort and predicate to make queries fast.
Per-tab navigation stacks with StatefulShellRoute
StatefulShellRoute keeps a separate Navigator and preserved state per branch, with a shared shell scaffold.
Explain the roles of ViewModel, Repository, and data source in MVVM
Tests your grasp of unidirectional data flow and separation of concerns in Android MVVM. A strong answer maps ViewModel to UI state, Repository to data coordination, and Room or Retrofit to I/O.
Explain ViewModel, Repository, and Data Source in MVVM
This tests your understanding of separation of concerns. A great answer defines ViewModel (UI state), Repository (data abstraction), and Data Sources (implementation), then explains the unidirectional data flow.
Explain ViewModel, Repository, and Data Source in MVVM
This tests your grasp of separation of concerns in Android. A good answer defines ViewModel, Repository, and Data Source roles, then traces the unidirectional data flow. A red flag is having the ViewModel directly access a data source like Retrofit.
Platform-specific file extensions
Name files Component.ios.js and Component.android.js; import without the extension and the bundler picks the right one per platform.
Bulk-import large JSON into Core Data efficiently
Use NSBatchInsertRequest to write rows directly to the store, bypassing context object materialization, for huge memory and speed wins; limitation is it skips validation, relationships, and does not notify…
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