Intermediate interview questions in Mobile Dev, page 5
How does a ViewModel survive configuration changes?
Tests understanding of lifecycle-aware components. ViewModels are retained by a ViewModelStore owned by the Activity/Fragment, which survives configuration changes. The ViewModel is cleared only when its scope is permanently finished.
How does a ViewModel survive configuration changes?
Tests understanding of ViewModel's scope, separate from the Activity lifecycle. A ViewModel is retained by a ViewModelStore, which persists across configuration changes. The new Activity instance then reconnects to the same ViewModel.
How do you complete a file download after the app backgrounds?
This tests iOS background execution and URLSession background transfers. Configure a background URLSession, handle AppDelegate events, and respect the 30-second completion handler limit. Never claim NSTimer or beginBackgroundTask sustains background downloads.
How do Flexible and Expanded differ in a Row or Column?
Tests Flutter main-axis flex constraints. Key point: Flexible uses FlexFit.loose so the child may be smaller than its space share; Expanded uses FlexFit.tight so the child must fill its share.
Describe the back stack for A to B to C with singleTask
Tests singleTask plus taskAffinity, not rote memorization. With default affinity, C sits atop B in the same task; if C already existed, the system clears B and delivers onNewIntent. Red flag: claiming singleTask always spawns a new task.
Describe the back stack for A -> B -> C with singleTask
Tests understanding of the singleTask launch mode. A great answer explains that launching C destroys B, as singleTask clears all activities above it in the task. The final back stack becomes [A, C]. A red flag is confusing this with singleTop.
singleTask Launch Mode: A -> B -> C Back Stack
This tests your understanding of Android's singleTask launch mode and task management. A good answer explains that A and B form a stack in one task, while C launches into a new, separate task, becoming its root.
How does the Coordinator pattern decouple navigation, and what are its components?
This tests iOS separation of concerns. Explain that Coordinators extract navigation logic from view controllers for reuse, and describe AppCoordinator tree with child coordinators. A red flag is treating it as a router or ignoring parent-child retention.
Fix RenderFlex overflow in Row with long truncating text
Wrap Text in Expanded; set overflow to TextOverflow.ellipsis and maxLines: 1; leave siblings unwrapped.
When and why use a Foreground Service on API 26+?
Tests background execution limits. Good answer: use for noticeable long-running work; declare FOREGROUND_SERVICE, show a notification, and respect API 26 background start limits. Red flag: calling it invisible work or omitting the notification.
When and why to use a Foreground Service?
Tests your grasp of Android's background execution limits. A great answer explains they're for user-visible tasks like music playback, requires startForegroundService(), and must show a notification within 5 seconds.
When and why use a Foreground Service on modern Android?
Tests understanding of background work restrictions. A great answer defines the use case for user-visible tasks, explains the mandatory notification, and details the startForegroundService() flow.
Describe a strategy for ListView on phones and GridView on tablets
This tests Flutter adaptive layout skills. Use LayoutBuilder or MediaQuery to read screen width, pick a breakpoint near 600 dp, and return ListView or GridView conditionally.
Static vs dynamic BroadcastReceiver registration and modern Android implications
Tests background limits, lifecycle coupling. Static manifest receivers survive app death but API 26 blocks most implicit broadcasts; dynamic receivers run with the context and must be unregistered. Red flag: static registration handles all implicit broadcasts.
Static vs. Dynamic BroadcastReceivers: Implications & Restrictions
This tests your grasp of Android's background restrictions. Explain that static receivers live with the app but are restricted post-API 26, while dynamic receivers are tied to a component's lifecycle. Ignoring modern API restrictions is a major red flag.
Static vs. Dynamic BroadcastReceivers: Implications and Restrictions
This tests your knowledge of Android's background execution limits. A good answer defines static and dynamic registration, explains the restrictions since Android 7/8, and gives use cases. A red flag is ignoring the modern API limitations.
Context re-renders when unrelated value changes
Every consumer re-renders when the Provider value reference changes, regardless of which field it uses; fix by splitting into separate contexts or memoizing and selecting.
Redux principles: store, actions, reducers
One store holds all state; actions are plain objects describing what happened; pure reducers compute the next immutable state from current state and action; dispatch drives the cycle.
Handling async API calls in Redux
Middleware intercepts dispatched actions, Thunk dispatches functions for simple flows, Saga uses generators for complex orchestration.
Explain the Coordinator pattern and the navigation problem it solves in MVC
This tests if you see view controllers bloat from absorbing navigation flow. A good answer names 3 problems (delegate bloat, massive view controllers, embedded routing) and says coordinators own creation and routing.
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