Make your Flutter apps feel lightning fast

When users interact with your app, speed matters. Optimistic state management can make your Flutter apps feel instantaneous by updating the UI immediately after an action, even before the server responds. Recently, the Flutter team has published a great guide about this technique: https://docs.flutter.dev/cookbook/architecture/optimistic-state.

What are Optimistic Updates?

It’s simple:

1. Predict the result of a user action and update the UI instantly.
2. Confirm the action with the server in the background.
3. Roll back if the server disagrees.

For example, a "like" button:

• Tap it → Instantly shows as "liked."
• Server confirms → All good.
• Server fails → Revert and notify the user.

How to Implement in Flutter

With Bloc, optimistic updates are a breeze. Here’s how you can handle adding a task to a todo list:

void addTask(Task task) {
  // Optimistically update the UI
  emit(state.copyWith(tasks: [...state.tasks, task]));

  // Sync with the server
  try {
    await api.addTask(task);
  } catch (_) {
    // Roll back if it fails
    emit(state.copyWith(
      tasks: state.tasks.where((t) => t.id != task.id).toList(),
    ));
  }
}        

Why It Matters

• Feels instant: No more waiting for server responses.
• Better UX: Keeps users engaged.
• Easy to implement: Flutter’s reactive framework makes it simple.

Quick Tips

1. Handle errors gracefully with clear user feedback.
2. Test rollback scenarios to ensure a smooth experience.
3. Be cautious with overlapping optimistic actions.

Optimistic updates are about creating the illusion of speed while maintaining reliability. Have you used this approach in your apps? Share your thoughts!