---
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:

```javascript
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


---
Source attribution: aj-geddes
Original project: https://github.com/aj-geddes/useful-ai-prompts/blob/3f5182cfd739fc113f4af5244a1cf342ad7f7911/skills/mobile-offline-support/SKILL.md
License: MIT
License information: https://opensource.org/license/mit
Original upstream instructions; downloaded from Dave AI.

## Upstream license notice

MIT License

Copyright (c) 2025 AJ Geddes

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.


# Dave AI resource metadata

Creator / publisher: aj-geddes
Original project: https://github.com/aj-geddes/useful-ai-prompts/blob/3f5182cfd739fc113f4af5244a1cf342ad7f7911/skills/mobile-offline-support/SKILL.md
Attribution basis: Source repository record

Fields of work: Development & Engineering, Product Management
Roles: Frontend Developer, Mobile Developer, Product Manager
Specialties: API, Mobile
Tools: Asyncstorage, React Native, Realm, Sqlite
Country applicability: Country not specified
Classification basis: Source catalog labels
Instruction SHA-256: 9ff606a3b527c646e2f0969ac110924912d6eb70548e6db047426850d84e7d46