Flutter State Persistence with Hydrated BLoC: A Step-by-Step Guide

State Persistence with Hydrated BLoC in Flutter: A Seamless User Experience

In the world of mobile app development, providing a seamless user experience is crucial for retaining users. One key aspect of achieving this is state persistence, which ensures that the app remembers its previous state even after it’s closed or restarted. In this article, we’ll explore how to implement state persistence in Flutter using Hydrated BLoC.

What is Hydrated BLoC?

Hydrated BLoC is an extension of the popular BLoC (Business Logic Component) library, which provides a simple and efficient way to manage state in Flutter apps. Hydrated BLoC takes it a step further by providing out-of-the-box persistence for your app’s state.

Why Use Hydrated BLoC?

By using Hydrated BLoC, you can ensure that your app remembers its previous state, even after it’s closed or restarted. This provides a seamless user experience, as users don’t have to re-enter data or navigate back to their previous location. Additionally, Hydrated BLoC eliminates the need to write complex code to save and restore state, making it a convenient solution for developers.

Getting Started with Hydrated BLoC

To get started with Hydrated BLoC, you’ll need to add the necessary dependencies to your project. You’ll also need to configure Hydrated BLoC to persist data on your local storage. Here’s an example of how to do this:

“`dart
import ‘package:flutter/material.dart’;
import ‘package:hydratedbloc/hydratedbloc.dart’;

void main() async {
WidgetsFlutterBinding.ensureInitialized();
await HydratedStorage.build();
runApp(MyApp());
}
“`

Creating a Hydrated BLoC

To create a Hydrated BLoC, you’ll need to define a class that extends HydratedBloc or uses the HydratedMixin. Here’s an example of a simple Hydrated BLoC that generates random numbers:

“`dart
class RandomNumberBloc extends HydratedBloc {
@override
int get initialState => 0;

@override
Stream mapEventToState(RandomNumberEvent event) async* {
if (event is GenerateRandomNumber) {
yield Random().nextInt(100);
}
}

@override
int fromJson(Map json) => json[‘randomNumber’];

@override
Map toJson(int state) => {‘randomNumber’: state};
}
“`

Storing and Retrieving State

Hydrated BLoC uses Hive under the hood to store and retrieve state. When you define a Hydrated BLoC, you’ll need to override the fromJson and toJson methods to serialize and deserialize your state. Here’s an example of how to do this:

“`dart
@override
int fromJson(Map json) => json[‘randomNumber’];

@Override
Map toJson(int state) => {‘randomNumber’: state};
“`

By following these steps, you can implement state persistence in your Flutter app using Hydrated BLoC. This will provide a seamless user experience, as your app will remember its previous state even after it’s closed or restarted.