Easy everything in Mobile Dev, page 4
When is UserDefaults right, what are its limits, and native types?
Tests if you treat UserDefaults as a small preference store, not a database. Good answers name native plist types, cite no encryption and small size limits, and name Core Data or Keychain for heavy or sensitive data. Red flag: storing images or passwords.
Implement SwiftUI navigation between list and detail with product ID
Tests modern SwiftUI navigation and clean data flow. Great answer: NavigationStack with NavigationLink(value:) and navigationDestination(for:), plus a bound path for programmatic control.
UIViewController lifecycle states: network vs geometry updates
Tests UIViewController lifecycle states and separation of data vs layout. Strong answers list loadView to viewDidDisappear, start network in viewDidLoad or viewWillAppear, and geometry in viewDidLayoutSubviews. Red flag: network calls inside layout methods.
What is @State in SwiftUI and how does it affect the view?
Tests declarative data flow ownership. A strong answer defines @State as private value-type storage owned by the view that triggers a body re-evaluation on mutation. Red flag: confusing it with external data sources like @ObservedObject or @Binding.
When should you use frame-based layout versus Auto Layout?
Frames suit static or high-frequency UI like particle systems; Auto Layout handles rotation, Dynamic Type, localization, and split screen.
What LLDB command prints a UIView description versus an Int?
Tests LLDB formatting at breakpoints. Great answers: po invokes description or debugDescription on objects, while p evaluates and prints raw primitive values with type info. Red flag: mixing them up or recommending console print instead of LLDB.
Difference between .xcodeproj and .xcworkspace, and when to use a workspace
Tests your mental model of Xcode build containers. A project defines one buildable unit; a workspace groups multiple projects so they build together and share derived data. Use it for package managers or modular codebases.
Explain protocols and how extensions provide default implementations
Tests behavior sharing without inheritance. A strong answer defines protocols as requirements, shows extensions injecting default implementations, and contrasts this with base-class inheritance.
Swift struct vs class: differences and when to choose each
Tests value vs reference semantics and let mutability. Strong answers contrast copy behavior with shared references, note allocation tendencies, and choose struct for value semantics or class for identity.
What is an optional in Swift? Demonstrate two safe unwrapping methods.
This checks Swift type safety and nil-handling. A strong answer defines Optional as an enum, demonstrates if let binding, and shows the nil-coalescing operator ?? for defaults. Avoid suggesting force-unwrapping with ! as a safe pattern.
What is the difference between let and var in Swift?
This tests value semantics beyond syntax. A strong answer defines let as immutable and var as mutable, notes that let on a reference type only fixes the pointer, and cites clearer intent and compiler optimization.
UserNotifications Framework: iOS Alert Gatekeeper
UserNotifications is the gatekeeper between your app and the lock screen. You use it to request permission and schedule local or push alerts on iOS. Send a notification before authorization and the system silently drops it.
Flutter's Widget, Element, and RenderObject trees: roles and relationships
Tests your mental model of Flutter's rendering layers. Strong answer: Widget is immutable configuration; Element is the mutable lifecycle manager owning the RenderObject; RenderObject is the concrete layout and paint entity.
Why use const for Flutter widgets and how does it improve performance?
Tests widget canonicalization and rebuild short-circuiting. Strong answer: const enables instance reuse and skips subtree rebuilds on parent updates, reducing allocations.
How would you manage different backend environments in a Flutter project?
Tests Flutter build flavors and compile-time config injection. A strong answer uses dart-define or flavor-specific entry points plus an EnvironmentConfig abstraction. A red flag is manually swapping hard-coded base URLs before each build.
Flutter command for an Android release build and APK vs AAB difference.
Flutter CLI release commands and Android distribution formats. Name flutter build apk and flutter build appbundle; note AAB lets Google Play generate optimized APKs per device while APK is a single direct-install file.
How do you verify a Text widget with 'Hello' is present?
Find.text('Hello') locates the widget; expect(finder, findsOneWidget) asserts exactly one exists.
Unit, widget, and integration test differences in Flutter
Tests your grasp of Flutter's test pyramid and isolation levels. Unit tests check pure Dart logic; widget tests verify UI in a headless environment; integration tests exercise the full app on a device. Red flag: saying widget tests require an emulator.
Explain the purpose of MethodChannel and how it enables Dart-to-native calls
MethodChannel lets Dart encode a method call; the platform host decodes it on the main thread, runs native code, and returns an async result.
What native iOS and Android config does the Flutter camera plugin need?
Tests native platform knowledge beyond Dart. iOS requires NSCameraUsageDescription and NSMicrophoneUsageDescription in Info.plist. Android needs minSdk 24 and choosing between CameraX or Camera2 implementations.
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