Interview questions in Mobile Dev, page 24
Adding a Swift Package dependency in Xcode
Add via File menu, paste the repo URL, choose a version rule like up-to-next-major, link the product to your target.
MethodChannel data flow and type marshalling
Dart invokeMethod sends a StandardMessageCodec-serialized payload to native, which returns a primitive or map; complex objects must be reduced to supported types.
When would you choose Foreground Service over WorkManager?
Tests immediate user-visible work versus deferrable jobs. Strong answers cite a notification-driven use case the user actively expects, like live navigation or a workout. Red flag: claiming WorkManager replaces real-time foreground tasks.
What data types cross the bridge, and their limits?
Only JSON-serializable types cross — strings, numbers, booleans, null, arrays, maps; functions and native object handles cannot. Handle complex data via ids, base64, or JSI host objects.
Package.swift manifest: library vs executable products
The manifest declares name, targets, dependencies, and products; a library is consumed by other code while an executable produces a runnable binary with an entry point.
When to choose EventChannel over MethodChannel and native setup
It tests streaming versus one-shot platform communication. Pick EventChannel for ongoing native events like sensor data; register a StreamHandler on Android or iOS that feeds an event sink, then consume in Dart via receiveBroadcastStream.
Explain Structured Concurrency in Kotlin Coroutines
Structured concurrency binds coroutines to a scope; parent cancellation propagates to all children, preventing leaks.
Contrast the legacy bridge with JSI
Bridge is async, serialized JSON, and batched; JSI enables direct synchronous C++ calls with no serialization, cutting latency and enabling lazy native modules.
Modularizing a monolithic iOS app
Extract low-dependency, high-reuse leaf code first behind clear interfaces, enforce boundaries, iterate inward.
What is a Platform View and why is it crucial?
Tests embedding native UI when Flutter widgets fall short. Strong answers define Platform Views as native embeddings, cite maps or WebView, and contrast Hybrid Composition's native hierarchy with Virtual Display's texture rasterization.
Android 12 foreground service restrictions and WorkManager expedited jobs
Tests Android 12 background-start limits. A great answer covers: the API 31 ban on background FGS starts, BOOT_COMPLETED exceptions, and WorkManager setExpedited with out-of-quota fallback. Red flag: starting an FGS in a BroadcastReceiver ignoring quota.
Direct events vs bubbling events in native components
Direct events fire only on the originating component; bubbling events propagate up the component tree like the DOM, allowing parent capture.
Static library versus dynamic framework linking
Static code is copied into the executable at build time; dynamic is loaded at launch by dyld. Trade-off: static bloats the binary but avoids load cost; many dynamic frameworks slow launch.
Safely gating native OS version APIs in a custom Flutter plugin
Tests platform channel contracts and defensive native coding. Gate native calls with OS version checks, return result.error with an UNSUPPORTED code, handle PlatformException in Dart, and avoid Dart-only checks.
What is the difference between test and androidTest source sets?
Say test runs on the JVM for unit tests mocking Android classes, while androidTest runs on device for instrumented tests.
What are the three pillars of the New Architecture?
JSI for direct JS-native calls, Fabric as the new renderer, and TurboModules for lazy native modules, all unified by CodeGen for type-safe bindings.
Developing a local Swift Package alongside an app
Add the package as a local dependency by dragging its folder into the project or workspace, so Xcode references the source on disk and rebuilds edits immediately.
Present full-screen native SDK UI from Flutter and return a result
This tests platform channel architecture for full-screen native UI delegation. Use MethodChannel to launch the native controller, retain the async result callback, serialize the dismissal payload back to Dart, and avoid PlatformView for modal flows.
Why mock a Repository dependency in a ViewModel unit test?
This tests your grasp of test isolation. A great answer says mocking eliminates real database or network dependencies so you can verify ViewModel state changes in isolation. A red flag is insisting on using the real Repository inside the unit test.
What do the spec file and CodeGen do in migration?
The spec file declares the component's typed props and events; CodeGen reads it at build time to generate type-safe C++/native and JS glue, catching mismatches early.
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