Building Reddit’s iOS and Android app

TL;DR

Reddit's mobile engineering teams modernize their codebase and improve user experience through strategic technological updates.

Transcript

AI coding tools. I'm interested how much do you use the current ones? What do you use? What is working? I think Apple's built-in Xcode one is perfectly fine. I use it a tremendous amount. Like I feel like chat GPT has officially replaced my knowledge of Git. I can never remember how to use Git invocations properly. So I just pop open a window and b... Read More

Key Insights

• 😣 Reddit's shift from REST to GraphQL significantly improved data handling efficiency and application responsiveness.
• 👨‍💻 AI coding tools are primarily acting as advanced autocompletion features rather than a complete solution for coding tasks.
• 😮 Developer satisfaction has risen through a more structured platform team environment, which enhances collaboration and supports engineers.
• 🏛️ Lengthy build times were a major pain point that necessitated modernization efforts, leading to reduced times of under 10 minutes for incremental builds.
• ☠️ The complexity introduced by server-driven UI architectures needs careful management to prevent issues such as redundant data fetching and increased error rates.
• 👥 Internal transfers from feature teams to platform teams provide valuable insights as engineers bring first-hand experience of user challenges into their new roles.
• ❤️‍🩹 Greater emphasis on improving DevX has translated into observable performance benefits for both end-users and mobile engineers.

Questions & Answers

Q: What motivated Reddit to transition from REST to GraphQL for their API?

The migration aimed to enhance data handling efficiency and provide a clearer contract between the client and the server. This transition was crucial for improving overall app performance, reducing latency, and allowing for more dynamic interactions by enabling the frontend to specify exactly what data to retrieve, unlike the often rigid structure of RESTful APIs.

Q: How have AI coding tools influenced the development workflow at Reddit?

AI coding tools have been utilized primarily as advanced autocomplete systems that assist developers by providing coding suggestions and explanations. They serve as a knowledge resource for Git commands and coding struggles, although there remains skepticism about their capability to produce reliable code autonomously for complex tasks.

Q: What metrics indicate the success of the modernization efforts within Reddit's mobile teams?

Post-modernization, improvements were observed in developer satisfaction scores, reduced build times, lower crash rates, and faster feature deployment. Performance metrics, such as startup times and stability, also showed significant enhancements, indicating a positive impact on both developer efficiency and user experience.

Q: How has the organizational structure affected mobile engineers at Reddit?

The establishment of dedicated platform teams for both iOS and Android has allowed for focused expertise and better support for feature teams. This change has made onboarding easier and created a more collaborative environment, enabling engineers to solve shared challenges effectively.

Q: What challenges did the mobile engineering teams face during the modernization process?

Some challenges included legacy code conflicts, lengthy build times, and the need for comprehensive test infrastructure. Adapting to new frameworks while diagnosing existing performance issues required significant effort and collaboration across multiple teams and platforms.

Q: What lessons were learned from the implementation of server-driven UI in mobile applications?

Server-driven UI has shown partial success; however, challenges arose such as double-fetching data and creating bugs due to discrepancies between server and client-side logic. The importance of ensuring client knowledge in server-driven scenarios highlighted the complexity and potential pitfalls of this architecture.

Q: What traits are vital for engineers aspiring to work on Reddit's mobile platform teams?

Engineers should have a strong foundation in core engineering principles, a willingness to take ownership of their work, and an interest in DevX. Experience in feature teams or a background in working across various system designs can also enhance their candidacy, alongside a collaborative attitude towards solving problems.

Q: How is the future of mobile development at Reddit expected to evolve beyond the current modernization efforts?

The focus will likely shift towards further refining user experience by exploring emerging technologies such as Swift UI for iOS, optimizing server interactions, and potentially integrating more sophisticated AI tools into the development process to enhance both coding efficiency and application performance.

Summary & Key Takeaways

• Reddit's mobile engineering teams have undergone significant modernization by transitioning from a REST to a GraphQL API, enhancing performance and usability for both iOS and Android platforms.

• The integration of AI coding tools has transformed coding practices, allowing developers to leverage efficient autocompletion features, although limitations in providing complete coding solutions remain.

• A dedicated focus on improving developer experience (DevX) has resulted in higher satisfaction among engineers, reduced build times, and increased application stability, ultimately benefiting the end user.