System2 Fitness: Rewriting the App with React Native cover

System2 Fitness: Rewriting the App with React Native

Partnered with System2 Fitness to rebuild their app, transitioning from Cordova to React Native, and building native integrations for Apple Watch.

At Variant Systems, we partnered with System2 Fitness, a fitness app company, to help them modernize and rewrite their mobile app. The goal was to evolve their existing app built on Ionic Cordova and Firebase, which was facing limitations in performance, feature addition, and scalability.

🧠 The Challenge

System2 Fitness needed to move away from their existing stack, as it wasn’t meeting their demands for new features and high-quality performance. The challenge was to choose the right framework — React Native or Flutter — to rebuild the app from scratch.

We worked closely with the System2 Fitness engineering team to evaluate the pros and cons of both frameworks. Our goal was to assess how each framework aligned with their needs and preferences.

🔧 Our Contribution

Here’s how we helped System2 Fitness:

  • Tech Stack Evaluation: We initiated the project by understanding the team’s preferences and technical requirements. We ran small POCs (Proof of Concepts) for both React Native and Flutter to test performance, developer experience, and compatibility with their existing backend infrastructure.
  • Built a Framework Comparison Tool: To involve the team in the decision-making process, we created a detailed survey-style website, asking engineers to rate their experiences with each framework based on factors like ease of use, performance, and personal preference. This helped us gather objective data and made the final decision to choose React Native.
  • App Rewriting: Once React Native was chosen, we helped System2 Fitness rewrite the entire app from Cordova to React Native, working closely with their engineering team to handle critical app components, testing, and app publishing infrastructure using Expo.
  • WatchOS Integration: We built a watchOS app from scratch, which included writing a native connector for the React Native Expo app. This allowed seamless communication between the mobile app and Apple Watch, enabling features like sharing Apple Health Data and messaging.
  • Dynamic App Icons: One of the unique features we built was an Expo native module to allow dynamic app icon changes at runtime. This was later open-sourced as expo-dynamic-app-icon, making it available to the broader React Native community.
  • Ongoing Leadership: As we rewrote the app, we continued to lead the project, providing ongoing code reviews, architecture reviews, and educating the team on best practices for mobile app development.

Our developers worked as an extension of the System2 Fitness team, bringing our expertise in mobile app development to deliver a top-quality, scalable solution.

🚀 Results

Through our collaboration, we achieved:

  • A successful app rewrite that improved performance, scalability, and user experience, using React Native as the chosen framework.
  • Seamless Apple Watch integration, allowing users to sync health data and enjoy a connected fitness experience across devices.
  • Dynamic app icon functionality, giving users a personalized app experience and enhancing engagement.
  • Improved app architecture, making the app more maintainable, flexible, and ready for future feature development.
  • Educational growth for the internal team, who gained valuable knowledge in mobile app development, testing, and code quality through our collaboration.
  • Improved App store ratings and customer feedback was full of joy and how this new update felt extremely responsive and is fun to use.

🛠 Tech Stack

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