From the community: How to set up feature flags in Flutter

I’m a software developer. My team uses both Unleash and Flutter to publish our app on mobile platforms.

Let’s talk about how you could use feature flags in Flutter to ship applications more efficiently. 

How to set up Unleash

If you haven’t already, you should start by setting up Unleash. It’s pretty simple. Make sure you install Git and Docker first. 

Head to Unleash’s documentation for more on setting up Unleash.

Integrating Unleash in Flutter

Now that we have created our Unleash instance, let’s dive into integrating our first feature flag in Flutter.

For this article we’ll integrate feature flags into one of my demo applications. The application is quite simple, and showcases the use of the Unsplash API.

Here’s a screenshot:

Let’s quickly enable and disable the image details page. You’ll do this through toggling a feature flag in Unleash. 

You’ll be able to control behavior through an Unleash instance without making any changes to the code.

In your Unleash instance, create a new feature flag called “isImageDetailsEnabled”.

By default, set the flag to “false,” which means the Image details feature will be disabled.  Choose the toggle type called “Release”.

For the implementation, you’ll use the “unleash_proxy_client_flutter” package. This package facilitates integration with Unleash. This way you can easily manage feature flag behavior in your Flutter application.

To install the “unleash_proxy_client_flutter” package, you have two options. You can either manually add the package in the `pubspec.yaml` file, or you can use the `flutter pub add` command.

After successfully installing the package, the next step is to initialize Unleash in your Flutter app. This sets up the necessary configurations using API tokens and prepares Unleash for feature flag management.

Given that the project follows clean architecture and Test-Driven Development (TDD) principles, you’ll want to create an abstract layer to interact with the Unleash client.

This abstraction will help you easily test Unleash functionalities while isolated from the rest of the application.

Once you have your configuration in place, the next step is to create the `UnleashClient` and add it to our service locator class, along with our `UnleashConfig`.

To display the image on the screen, you should utilize the custom `ImageTile` widget. You’ll then make adjustments to the widget using the `UnleashConfig` in order to navigate to the “ImageDetailsPage.”

This way you’ll enable dynamic navigation based on the flag’s status. Your users will thank you for it. 

Here you’ll enable the flag “isImageDetailsEnabled” within Unleash, then activate your image details feature in the application.

Voila! You’ve activated your desired functionality. You’ve also made sure that users can access image details depending on the state of the flag.  

Video: See flutter and Unleash in action.

Conclusion

Feature management is a way to develop software that gives a lot of flexibility and control when incorporated in Flutter.

With Unleash integrated into Flutter, you can do things like:

• Tailor onboarding experiences
• Orchestrate time-limited in-app offers,
• Optimize a release pipeline

Your team can also use Flutter and Unleash to test different versions with diverse groups of users. This is a great way to gain insightful user metrics about a feature before rolling it out to a larger audience. It also makes your releases a lot less risky.

For instance, you can use A/B testing to test different search bar positions in the Unsplash sample app. You can then use metrics from your users to decide which position to keep.

Some best practices include setting up a clean and manageable codebase, while developing proper naming conventions for your flags. 

Make sure to revisit your flags from time to time. You should remove obsolete flags to keep your code clean and avoid technical debt.

That’s it for today. I hope you found this helpful. If you’re just getting started with feature flagging with Flutter and Unleash, I think you’ll really enjoy your journey.

Want to deep dive into the code used for this article? It’s all on GitHub.