React Native Background Tasks

Quick Guide: Background tasks in React Native are heavily constrained by OS power management. Use expo-background-task (Expo) or react-native-background-fetch (bare RN) for periodic fetch. Use expo-location for background location tracking. iOS gives ~30s for refresh tasks (BGAppRefreshTask) and several minutes for processing tasks (BGProcessingTask). Android enforces 15-minute minimum intervals via WorkManager and restricts execution in Doze mode. Always call finish() or return a result when done -- the OS will terminate tasks that exceed their time budget.

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CRITICAL: Before Using This Skill

(You MUST define tasks in the top-level scope (global) -- tasks defined inside React components or lifecycle methods will NOT be registered when the app starts from the background)

(You MUST call finish(taskId) or return a BackgroundTaskResult when task execution completes -- failing to signal completion causes the OS to penalize or kill your app)

(You MUST request background permissions explicitly on both platforms -- iOS requires Info.plist UIBackgroundModes entries, Android requires manifest permissions)

(You MUST handle the OS killing your task at any time -- use expiration listeners on iOS and timeout callbacks on Android to clean up gracefully)

(You MUST keep background work minimal -- sync only changed data, avoid heavy computation, respect the ~30s iOS refresh limit)