flutter_local_prefs

flutter_local_prefs is a Flutter plugin that allows you to securely store, retrieve, and manage local preferences across both Android and iOS platforms. With this package, you can maintain two categories of data:

1. Persistent Data (isPersistent: true) – remains even after logout or app restarts.
2. Non-Persistent Data (isPersistent: false) – cleared when you decide (e.g., during logout).

All stored preferences are encrypted, ensuring data protection and privacy.

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📌 Why Use Persistent and Non-Persistent Data?

Sometimes you may want certain preferences (e.g., user settings) to remain even after logout, but clear others (e.g., user session tokens). By separating your data into persistent and non-persistent, you can easily control which data to keep or remove.

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📢 Pre-Requisites

Android

Ensure your minSdkVersion is set to 19 or higher in your android/app/build.gradle:

minSdkVersion 19

iOS

Ensure the minimum supported iOS version is 12.0 in your project configuration.

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🚀 Installation

Add the dependency to your pubspec.yaml:

dependencies:
  flutter_local_prefs: ^0.0.4

Then import the package:

import 'package:flutter_local_prefs/flutter_local_prefs.dart';

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💾 Storing Data

Persistent Data (e.g., keep after logout)

// Create an instance
FlutterLocalPrefs flutterLocalPrefs = FlutterLocalPrefs();

// Save a persistent string
await flutterLocalPrefs.saveData(
  object: "Welcome!",
  key: "welcomeMessage",
  isPersistent: true,
);

// Save a persistent boolean
await flutterLocalPrefs.saveData(
  object: true,
  key: "darkModeEnabled",
  isPersistent: true,
);

Non-Persistent Data (e.g., clear on logout)

// Save a non-persistent (temporary) token
await flutterLocalPrefs.saveData(
  object: "ABC123",
  key: "sessionToken",
  isPersistent: false,
);

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📥 Retrieving Data

// Retrieve persistent data
String message = await flutterLocalPrefs.getString(
  key: "welcomeMessage",
  isPersistent: true,
);

bool darkMode = await flutterLocalPrefs.getBool(
  key: "darkModeEnabled",
  isPersistent: true,
);

// Retrieve non-persistent data
String sessionToken = await flutterLocalPrefs.getString(
  key: "sessionToken",
  isPersistent: false,
);

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🗑 Removing Data

Remove Non-Persistent Data During Logout

If you only want to clear non-persistent data at logout (like session info), use:

await flutterLocalPrefs.removeAll(
  isPersistent: false,
);

This removes all data that was saved with isPersistent: false, while keeping data marked isPersistent: true.

Remove Persistent Data

If you also want to remove everything that was saved as persistent, call:

await flutterLocalPrefs.removeAll(
  isPersistent: true,
);

This clears all data with isPersistent: true.

Remove Specific Key

// Remove a single persistent key
await flutterLocalPrefs.remove(
  key: "darkModeEnabled",
  isPersistent: true,
);

// Remove a single non-persistent key
await flutterLocalPrefs.remove(
  key: "sessionToken",
  isPersistent: false,
);

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❓ Check if Key Exists

bool isDarkModeExists = await flutterLocalPrefs.contain(
  key: "darkModeEnabled",
  isPersistent: true,
);

bool hasSessionToken = await flutterLocalPrefs.contain(
  key: "sessionToken",
  isPersistent: false,
);

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📚 API Reference

Method	Description
saveData({required Object object, required String key, bool isPersistent})	Saves an object (String, int, bool, double, long) under a specific key. Set isPersistent: true for permanent.
getInt({required String key, bool isPersistent})	Retrieves an integer value. Use isPersistent: true for persistent data.
getString({required String key, bool isPersistent})	Retrieves a string value.
getBool({required String key, bool isPersistent})	Retrieves a boolean value.
getDouble({required String key, bool isPersistent})	Retrieves a double value.
getLong({required String key, bool isPersistent})	Retrieves a long integer value.
contain({required String key, bool isPersistent})	Checks if a key exists in persistent or non-persistent storage.
remove({required String key, bool isPersistent})	Removes a specific key-value pair from persistent or non-persistent storage.
removeAll({bool isPersistent})	Clears all data in either persistent or non-persistent storage.

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📌 Usage Example

A typical logout flow might:

1. Remove all non-persistent data (e.g., session tokens) so the user is effectively logged out.
2. Keep certain persistent preferences (e.g., user’s theme settings or saved language preference).

If you also want to wipe out persistent data, simply call removeAll(isPersistent: true).

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📜 License

This project is licensed under the MIT License.

For a full API reference, visit the official documentation.