What is the feature of using SharedPreferences in Flutter?

SharedPreferences provides a simple API for storing small amounts of data (primitive types: int, double, bool, String, List<String>) as key-value pairs. Data is stored asynchronously. This is suitable for storing user settings, flags, and other non-critical information.

Features:

• Ease of use: The API is lightweight and intuitive.
• Asynchronous operations: All read and write operations are asynchronous, preventing UI thread blocking.
• Limited set of types: Supports only primitive types and list of strings.
• Not suitable for large volumes or complex data: Inefficient for storing large data structures or many records.
• Platform dependence: Implementation is based on native data storage mechanisms (e.g., NSUserDefaults on iOS, SharedPreferences on Android).
• Not secure for confidential information: Data is stored in plain text, not suitable for passwords or sensitive data.
• Requires await for access: Getting an instance of SharedPreferences and performing read/write operations require using await.

Example usage:

// Getting an instance of SharedPreferences
final prefs = await SharedPreferences.getInstance();

// Writing data
await prefs.setInt('counter', 10);
await prefs.setBool('isDarkMode', true);
await prefs.setString('username', 'FlutterDev');
await prefs.setStringList('items', ['apple', 'banana']);

// Reading data
final counter = prefs.getInt('counter') ?? 0; // Using ?? for default value
final isDarkMode = prefs.getBool('isDarkMode') ?? false;
final username = prefs.getString('username');
final items = prefs.getStringList('items') ?? [];

// Removing data
await prefs.remove('username');
await prefs.clear(); // Removes all data