Expo SDK Packages Highlights Summary

Every highlight bullet from the 9 pages in this section, gathered on one page and grouped by the page it came from.

Expo SDK Basics

• npx expo install pins semver ranges tested against your SDK - plain npm install can drift
• Every Expo module version is validated against the expo package in package.json
• Config plugins require a development build or prebuild - Expo Go ignores many native plugins
• Import side effects at app entry for TaskManager and some native listeners
• Run npx expo doctor after SDK bumps to catch incompatible native modules early
• Unimodules share a single native bootstrap - one mismatched package breaks the whole binary

expo-notifications

• Request notification permission after an in-app rationale - not on first mount
• Android 13+ requires POST_NOTIFICATIONS - create channels before posting
• setNotificationHandler controls foreground banners on iOS
• Push tokens require a development build and EAS projectId - Expo Go is limited
• Register token server-side per device - rotate on reinstall and logout
• Import notification handlers at app entry before the first push arrives

expo-location

• Request When In Use first - upgrade to Always only when background is essential
• Info.plist and Android manifest strings must explain why background access exists
• Background location requires a development build and UIBackgroundModes
• Stop updates on unmount - forgotten watchers drain battery
• Geofencing uses TaskManager.defineTask in global scope
• Never ship vague permission copy - App Review rejects 'This app needs location'

expo-camera & expo-image-picker

• expo-camera for live preview; expo-image-picker for library selection
• Request camera permission after explaining why capture is needed
• Downscale images before upload - full-resolution URIs exhaust memory
• Use quality and allowsEditing options to cap payload size
• Revoke object URLs and clear large base64 strings after upload
• Config plugin microphone permission only when recording video with audio

expo-file-system

• SDK 57 introduces File, Directory, and Paths - prefer over string URI juggling
• documentDirectory persists; cacheDirectory is evictable by the OS
• Never store secrets in Files - use expo-secure-store
• Legacy API lives at expo-file-system/legacy during migration
• Download with File.downloadFileAsync or createDownloadTask for progress
• Store file paths in SQLite - not multi-MB blobs in the database

expo-secure-store & expo-crypto

• SecureStore maps to Keychain (iOS) and Keystore (Android) - not encrypted files
• ~2 KB per-item limit - store tokens, not JSON user profiles
• WHEN_UNLOCKED_THIS_DEVICE_ONLY excludes iCloud Keychain export
• expo-crypto provides SHA digests and secure random bytes - not password storage
• Clear SecureStore keys on logout alongside Query cache and navigation
• Auth tokens pair with auth-session patterns - never AsyncStorage

expo-updates (Client API)

• Updates.checkForUpdateAsync detects new JS bundles on your EAS Update channel
• fetchUpdateAsync downloads in background - reloadAsync applies on next launch or immediately
• Native changes still require a store build - OTA cannot add config plugins
• UseUpdates hook exposes checking/fetching state for in-app update UX
• Disable indiscriminate reload during active forms - prompt or defer to background
• Development builds skip production update channels - test on release profile

expo-task-manager & Background Tasks

• TaskManager.defineTask must run in global scope before React mounts
• expo-background-task schedules deferrable work - minimum 15 minute interval
• Location geofencing and background fetch share the same defineTask registry
• Return BackgroundTaskResult.Success or Failed - failed tasks may retry per OS policy
• No React hooks inside defineTask - open SQLite and storage imperatively
• iOS simulators do not run BGTaskScheduler - test on physical devices

Expo SDK Packages Best Practices

• 25 essentials for installing, permissioning, and operating Expo SDK modules
• Always npx expo install - never drift from the SDK compatibility matrix
• Pre-prompt before every OS permission dialog - especially notifications and location
• Graceful denial: Settings deep link, degraded mode, never infinite spinners
• Secrets in SecureStore; files in FileSystem; relational data in SQLite
• Background work is deferrable - foreground reconnect remains primary