What are SQLite and Shared Preferences?
SQLite is a lightweight, serverless database used for local data storage in mobile applications.
It stores data in a single file on the device, making it ideal for offline-first app development.
SQLite allows apps to read, write, and manage structured data efficiently without an internet connection. It is widely used in Flutter through plugins like SQLite for persistent storage.
Shared Preferences is a simple key-value storage system used in Flutter for storing small amounts of local data. Unlike databases, it stores flat, lightweight data such as login states, tokens, and user settings. Data has persisted across app launches, making it ideal for preferences and flags.
It uses native storage: XML on Android and NSUserDefaults on iOS. Flutter implements Shared Preferences using the shared preferences package for easy integration.
Benefits of Using SQLite and Shared Preferences
Using SQLite:
Offline Support: Enables the app to work without internet by storing data locally. This ensures uninterrupted access to essential features and data.
Fast Local Access: Data is read and written directly from the device. This improves app speed and responsiveness significantly.
Lightweight and Embedded: SQLite runs without a server and is embedded in the app. It’s perfect for mobile apps needing simple, local storage.
Easy to use: Integrates smoothly with Flutter using packages like SQLite. Developers can quickly implement and manage the local database.
Secure Storage: Supports data encryption for sensitive information. It adds a layer of security for local data handling.
Using Shared Preferences:
Simple to Use: Shared Preferences stores data as key-value pairs, so you don’t need to worry about setting up a database or designing complex schemas. This makes it very beginner-friendly and quick to implement for saving simple data.
Persistent Storage: Data saved with Shared Preferences stays stored on the device even after the app is closed or restarted.
Lightweight: It is designed to handle small amounts of data like user tokens, login status, or app theme settings. Because it’s lightweight, it doesn’t slow down your app or consume much storage space.
Platform-Independent: Shared Preferences uses native storage mechanisms on each platform — XML files on Android and NSUserDefaults on iOS. This abstraction allows you to write one Flutter code that works seamlessly on both platforms.
Implementing Offline Storage with SQLite and Shared Preferences in Flutter
Offline storage plays a vital role in mobile application development, especially in areas with limited or unreliable internet connectivity. SQLite is one of the most widely used databases for local storage because of its simplicity, speed, and ability to run without a separate database server.
In Flutter, developers commonly use the SQLite plugin to integrate SQLite. With it, you can define tables, insert, update, delete, and query data using simple SQL commands. This allows you to store structured data such as user details, app settings, cached API responses, or even complete form submissions locally on the user’s device. For example, imagine a travel booking app: if the user fills out a booking form but loses internet connection, the app can temporarily save that data in SQLite. Once the connection is restored, the app can sync that data to the server in the background.
Key steps in implementation:
- Define a model and database helper class.
- Create the database and required tables when the app initializes.
- Use CRUD operations (Create, Read, Update, Delete) to manage local data.
- Sync with the backend when the network is available.
Using SQLite not only boosts performance by reducing the number of API calls but also ensures a seamless user experience by enabling offline-first behaviour.
Offline storage is crucial for mobile apps, especially when internet access is slow or unavailable. Shared Preferences is a lightweight solution for storing simple key-value pairs locally on the device.
In Flutter, developers use the shared preferences package to save data such as user settings, login status, or flags indicating app state. This data persists even after the app is closed, ensuring that important preferences are remembered between sessions.
Key steps in implementation:
- Import and initialize the Shared Preferences instance.
- Save simple data like Booleans, strings, or integers with keys.
- Retrieve saved data during app startup or whenever needed.
Using Shared Preferences improves user experience by enabling quick access to essential data offline without complex database management.
Conclusion:
Both SQLite and Shared Preferences are essential tools for implementing offline storage in Flutter apps, but they serve different purposes. SQLite excels at managing complex, structured data with powerful querying capabilities, making it ideal for data-heavy applications. On the other hand, Shared Preferences offers a lightweight, simple way to store small pieces of data like user preferences and settings. Choosing the right storage solution depends on your app’s specific needs — for rich data and relationships, go with SQLite; for quick and easy key-value storage, Shared Preferences is the way to go. Mastering both will help you build robust, efficient, and user-friendly Flutter applications that work seamlessly offline.