React Native Case Studies & Practical Application 5

Question 1

A logistics app must scan barcodes continuously without the user pressing a button each time. Which implementation supports continuous scanning?

Accepted Answer

Use the Camera component's onBarCodeScanned prop with a cooldown flag

Answer

onBarCodeScanned fires automatically for each detected barcode; a cooldown flag prevents duplicate scans while keeping the camera live.

Question 2

A multi-tenant SaaS app must switch between different API environments (staging vs production) without rebuilding. What is the standard approach?

Accepted Answer

Use react-native-config to inject environment variables at build time per scheme/flavor

Answer

react-native-config reads .env files per build variant, injecting the correct API URL at build time without runtime switches.

Question 3

A shopping app shows a 'You left items in your cart' push notification 30 minutes after the user abandons checkout. What component handles this?

Accepted Answer

A server-side job that sends an FCM/APNs push 30 minutes after the last cart event

Answer

Abandoned-cart reminders require server-side scheduling because the app may not be running 30 minutes later to send a local notification.

Question 4

A telemedicine app shows a video call UI. During the call, incoming phone calls must not terminate the video session on Android. What API handles this?

Accepted Answer

ConnectionService API via react-native-callkeep to integrate with the system dialer

Answer

react-native-callkeep integrates with Android's ConnectionService to manage VOIP calls at the system level, preventing interruptions from cellular calls.

Question 5

A sports app must update live scores every 5 seconds while the screen is active. What is the most efficient pattern?

Accepted Answer

WebSocket connection opened once and closed when the component unmounts

Answer

A single persistent WebSocket connection receives server-pushed updates instantly with far less overhead than polling every 5 seconds.

React Native Practice Test

React Native Practice Test

React Native Case Studies & Practical Application 5