From Hours to Minutes: Making Your React Native CI Builds 20x Faster

The speakers outline common pipelines for JavaScript checks, native iOS and Android builds, end-to-end tests, and release previews. They say native builds can take 25 to 40 minutes, while caching dependencies, Xcode derived data, and C++ compilation can help but may be slow or unreliable. They recommend measuring cache performance because large caches can cost more time to retrieve than a fresh install.

Callstack’s open-source React Native Enterprise Framework builds on the history of the Community CLI and React Native’s move toward framework-based development. Its design emphasizes modularity, self-hosting, and incremental adoption for both existing React Native projects and native apps adding React Native. Teams can configure platforms, bundlers, plugins, and a remote cache provider.

The Expensify demo shows GitHub Actions workflows using the framework to find and reuse native build artifacts. The CLI calculates a fingerprint for the project and checks the remote cache; when it finds a match, it downloads the artifact, and when it does not, it builds locally. In the demonstrated setup, many workflows took about one or two minutes, while a fresh Android build could take around 38 minutes.

For every 25 repository changes at Expensify, about one triggered a native build; the other 24 were JavaScript or other non-native changes. The presenters report that this reduced native builds from every change to 4% of changes, cut monthly GitHub Actions costs for debug iOS and Android builds from about $6,000 to $317, and reduced compute for 25 builds from over 16 hours to about 90 minutes. They say release builds and end-to-end tests remain opportunities for further reuse.

The speakers describe creating a project with `npm create rnf-app` or migrating from the Community CLI, then adding remote caching as needed. They discuss integrating with Fastlane and implementing cache providers for other storage systems, while noting that GitHub Actions support is available out of the box. They also mention roadmap items including more cache providers, continuous native generation, out-of-tree platforms, and mobile micro-frontends.