/mobile-offline-support

name: mobile-offline-support
description: >
  Implement offline-first mobile apps with local storage, sync strategies, and
  conflict resolution. Covers AsyncStorage, Realm, SQLite, and background sync
  patterns.

Mobile Offline Support

Table of Contents

• [Overview](#overview)
• [When to Use](#when-to-use)
• [Quick Start](#quick-start)
• [Reference Guides](#reference-guides)
• [Best Practices](#best-practices)

Overview

Design offline-first mobile applications that provide seamless user experience regardless of connectivity.

When to Use

• Building apps that work without internet connection
• Implementing seamless sync when connectivity returns
• Handling data conflicts between device and server
• Reducing server load with intelligent caching
• Improving app responsiveness with local storage

Quick Start

Minimal working example:

import AsyncStorage from '@react-native-async-storage/async-storage';
import NetInfo from '@react-native-community/netinfo';

class StorageManager {
  static async saveItems(items) {
    try {
      await AsyncStorage.setItem(
        'items_cache',
        JSON.stringify({ data: items, timestamp: Date.now() })
      );
    } catch (error) {
      console.error('Failed to save items:', error);
    }
  }

  static async getItems() {
    try {
      const data = await AsyncStorage.getItem('items_cache');
      return data ? JSON.parse(data) : null;
    } catch (error) {
      console.error('Failed to retrieve items:', error);
      return null;
    }
  }

// ... (see reference guides for full implementation)

Reference Guides

Detailed implementations in the `references/` directory:

| Guide | Contents | |---|---| | [React Native Offline Storage](references/react-native-offline-storage.md) | React Native Offline Storage | | [iOS Core Data Implementation](references/ios-core-data-implementation.md) | iOS Core Data Implementation | | [Android Room Database](references/android-room-database.md) | Android Room Database |

Best Practices

✅ DO

• Implement robust local storage
• Use automatic sync when online
• Provide visual feedback for offline status
• Queue actions for later sync
• Handle conflicts gracefully
• Cache frequently accessed data
• Implement proper error recovery
• Test offline scenarios thoroughly
• Use compression for large data
• Monitor storage usage

❌ DON'T

• Assume constant connectivity
• Sync large files frequently
• Ignore storage limitations
• Force unnecessary syncing
• Lose data on offline mode
• Store sensitive data unencrypted
• Accumulate infinite queue items
• Ignore sync failures silently
• Sync in tight loops
• Deploy without offline testing