How to migrate an iOS app to Bazel

This guide will help you set up Bazel for your iOS project, including using rules_xcodeproj to generate Xcode projects and build them with Bazel. It also covers enabling remote caching, remote execution, and a Build Event Service (BES) endpoint to improve build performance and gain insights into your builds. 1. Install Bazel: Follow the installation instructions for your platform from the official Bazel website. 2. Create a new iOS project with rules_xcodeproj: Add rules_xcodeproj as a dependency in your WORKSPACE file, then create an xcodeproj target in your BUILD file. 3. Configure .bazelrc for remote caching and BES: Adjust the .bazelrc file to enable a remote cache, disable uploads for local development, and disable the disk cache on CI. Also configure it to upload events to a BES endpoint. 4. Cache warming with rules_xcodeproj: Use the --generator_output_groups=all_targets flag when running bazel run //:xcodeproj to build all targets under the same configuration that rules_xcodeproj uses, populating the remote cache with blobs that developers will then get cache hits on. 5. Optimize Bazel settings for better performance and compatibility. 6. Modularize your project to improve incremental compilation support from Bazel. 7. Profile and optimize build performance as needed. 8. Consider custom macros and rules to make specific workflows more efficient or easier to set up.