Easy interview questions in Mobile Dev, page 6
Provider package versus raw InheritedWidget
It removes boilerplate, adds lifecycle disposal and scoped reads, and exposes select for granular rebuilds.
Map JSON keys to differently named Codable properties
Declare a nested CodingKeys enum mapping userID to the raw value "user_id", or set the decoder's keyDecodingStrategy to convertFromSnakeCase for blanket conversion.
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.
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.
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.
Explain FutureBuilder and how it manages async UI states
This tests declarative async UI state management. Obtain the Future before build, pass it to FutureBuilder, and branch on snapshot.connectionState and hasError to render loading, data, or error states.
What are Room's three main components and their functions?
Tests whether you know Room's architectural layers. Name the three: Database holds config and is the access point; Entity represents a table schema; DAO defines SQL operations. Red flag: confusing DAOs with Repositories or claiming Room is a full ORM.
Purpose of factory fromJson constructor in Dart models
Factory fromJson centralizes deserialization, preprocesses Map values before instantiation, and keeps the primary constructor clean.
Why choose DataStore over SharedPreferences for a toggle?
This tests your grasp of modern Android storage safety beyond syntax. A strong answer names DataStore's async coroutines API, type safety, transactions, and migration support. A red flag is claiming SharedPreferences is simpler while ignoring ANR risk.
Implicit .animation() vs explicit withAnimation
.animation(value:) animates a view when a tracked value changes; withAnimation wraps the state mutation so all dependent views animate.
How do you define a Room table for a Kotlin data class?
Tests your grasp of the minimum Room entity contract. A strong answer cites Entity and PrimaryKey, notes Kotlin defaults work out of the box, and mentions ColumnInfo for renaming.
Add shadow and rounded corners to a UIView
CornerRadius needs masksToBounds true, but that clips the shadow; set shadowPath to keep both and stay performant.
Persisting key-value preferences across launches
AsyncStorage for simple non-sensitive key-value, MMKV for speed, SecureStore or Keychain for secrets.
Requesting runtime permissions on iOS and Android
Declare permissions in Info.plist and AndroidManifest, then check status and request at runtime just before use, handling granted, denied, and blocked.
Getting a one-time GPS location
Ensure permission, then call a getCurrentPosition wrapped in a promise (or Expo Location.getCurrentPositionAsync) with await inside try/catch, reading coords.latitude and longitude.
How would you use Retrofit to GET /posts/{id} and key components?
This checks your understanding of Retrofit's three-layer setup. You need a data class for JSON parsing, an interface with @GET and @Path, and a Retrofit.Builder with baseUrl and a converter.
When to use SQLite over key-value storage?
Tests structured-vs-flat storage judgment. Good answers cite relational data, complex queries, or multi-table schemas, then list adding the dependency, getting a path, opening with onCreate, and keeping a singleton.
How do you configure Moshi or Kotlinx.serialization for JSON key mismatches?
This tests library-specific field-mapping annotations. For Kotlinx.serialization use @SerialName with the JSON key; for Moshi use @Json with the name parameter. A red flag is confusing the two or using manual mapping instead of the built-in decorator.
Request the user's location one time
Add a usage description to Info.plist, set a CLLocationManager delegate, request when-in-use authorization, call requestLocation, handle didUpdateLocations and didFailWithError.
Play a remote video with AVFoundation
Wrap the URL in AVPlayerItem, feed it to AVPlayer, render with AVPlayerLayer added to the view's layer (or AVPlayerViewController for controls).
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