Simplifying state management in flutter with Bloc.
Published: 2024-04-14 15:49:34

Mobile app development is a dynamic world with a lot of interesting tools, techniques and solutions, one of these is state management. How you manage the state of your application can effectively make or break your use experience. To simply understand state management will mean something like changing the widget state within your application once a certain action has been performed. Take for example when data has been posted and should be displayed within the screen of your flutter  application without necessarily reloading the application itself, then the developer should understand how to manage this and thus comes in state management. Flutter over the years has emerged as a powerful platform to build attractive cross platform applications. State management is crucial especially placing in mind that any application will over time grow in its complexity.


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Flutter offers various state management solutions, with each solution having its strengths and different use cases under which they can be used. Among these solutions is Bloc (Business Logic Component). Since the emergence of bloc as a state management tool, it has managed to gain significant popularity as a result of its simplicity, scalability and predictability. The beauty of Bloc is its ability to separate business logic from the UI itself thus making your codebase more testable, intuitive and maintainable. While selecting a state management solution to use, it is good to remember that there is no one perfect solution. Choose a solution that works best for your team and your project. Bloc patterns in flutter will evolve around three core concepts : events, states and streams. An event will be triggered by the UI i.e. button press.

We can create a Stream in Dart by writing an async* (async generator) function.

`Stream<int> countStream(int max) async* {
    for (int i = 0; i < max; i++) {
        yield i;
    }
}
`

Understanding Bloc state management
1. Events: These are inputs to the Bloc, representing user interactions or any other trigger that leads to a change in the application state.
2. States: A state will represent the different snapshots of your application’s UI based on the current state of the data. Each change of state triggers a UI update, thus ensuring that your application remains responsive and reactive.
3. Bloc: This is responsible for processing incoming events, updating the state accordingly, and emits the new state to update the UI. This is where the business logic of the application resides.

Advantages of Bloc state management
Separation of concerns
This will involve isolating business logic from UI components, Bloc promotes a clean and clear codebase. With this separation there is guaranteed code readability, facilitated testing and enables easier collaboration among the team members.

Predictable state management
With clear event-to-state mappings, you can easily reason about how state changes occur in response to user interactions or other triggers. For the developer this predictability simplifies debugging and troubleshooting, leading to faster development cycles.

Reusability and scalability
This is achieved by encapsulating business login in reusable components.  As your application grows, you can compose multiple Blocs to handle different aspects of your app's state independently. This modular approach fosters maintainability and allows for easy integration of new features or updates without introducing unexpected side effects.

Implement Bloc State Management in Flutter
His easy simple step will help you implement Bloc state management in flutter:
1. Define Events: This will involve  identifying the different user interactions or triggers that will lead to a change in your application state and define corresponding event classes.
2. Define state: This is dependent on the data that drives your UI where you now define the various states of your application. Each state should encapsulate the data required to render the corresponding UI representation.
3. Create Bloc: Implement a Bloc class that extends Fluter’s ‘_Bloc_’ class from the ‘_flutter_bloc_’ package. This class will now help you handle incoming events, update the state accordingly, and emit the new state to notify the UI.
4. Handle Events: To process incoming events and update the state accordingly, you now have to implement event handlers within your Bloc class. You may use methods like ‘_mapEventToState_’ to define the logic for Transitioning between states based on the events that are received.
5. Integration with UI: You will now integrate the Bloc with the Flutter UI using widgets provided by the ‘_flutter_bloc_’ package, such as ‘BlocBuilder’ or ‘_BlocProvider_’. These widgets subscribe to the Bloc’s state updates and automatically rebuild the UI in response to the state change.

Using a Bloc
I hope you now get the basic concepts in Bloc State Management. We will now create an instance of a CounterBloc and put it in use as our example.

Basic Usage
`Future<void> main() async {
  final bloc = CounterBloc();
  print(bloc.state); // 0
  bloc.add(CounterIncrementPressed());
  await Future.delayed(Duration.zero);
  print(bloc.state); // 1
  await bloc.close();
}
`

From above, you ca see that we created a CounterBloc object. Next, since no additional states have yet to be emitted, we print the Bloc's initial state, which is its present state. The CounterIncrementPressed event is then added to cause a state change. Lastly, we call close on the Bloc to end the internal state stream and publish the Bloc's state once more, which changed from 0 to 1. Finally, we call close on the Bloc to close the internal state stream.

Stream Usage
Remember that a Bloc is a special type of steam, which means we can also subscribe to a Bloc for real-time updates to its state.

`Future<void> main() async {
  final bloc = CounterBloc();
  final subscription = bloc.stream.listen(print); // 1
  bloc.add(CounterIncrementPressed());
  await Future.delayed(Duration.zero);
  await subscription.cancel();
  await bloc.close();
}
`

We are calling print on each state change and subscribing to the CounterBloc in the sample above. Next, we add the CounterIncrementPressed event, which causes a new state to be emitted and activates the on EventHandler. Finally, when we decide we no longer wish to get updates, we will close the Bloc and phone to cancel the subscription.

Conclusion
Bloc state management provides a strong way to handle state in Flutter apps, encouraging predictability, scalability, and concern separation. Flutter developers may create reactive, scalable, and maintainable apps that offer a consistent user experience on all platforms by implementing the Bloc pattern.

It does not matter whether you are building a small-scale application or a large-scale enterprise solution, mastering Bloc state management can greatly simplify your development process and empower you to build high-quality Flutter apps with confidence. So why not give Bloc a try in your next Flutter project and experience the benefits firsthand?

Enjoy your coding, and may your Flutter journey be as smooth as a well-crafted Bloc.