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Introducing rules_xcodeproj 1.0

Brentley Jones
Brentley Jones, Developer Evangelist @ BuildBuddy

Almost exactly one year ago I wrote the first commit for rules_xcodeproj. Like a lot of software engineers, I’m pretty bad at estimating, and thought that I would be able to finish 1.0 in 2 to 4 months 😅. The longer development cycle was a result of an increased scope and level of quality that I came to expect for a proper 1.0 release. Over the course of the year, I believe the project has risen to meet my expectations, and today I’m happy to announce the release of version 1.0 of rules_xcodeproj!

Screenshot of a rules_xcodeproj generated project open in Xcode

The road to 1.0

The road to 1.0 has been an incredible journey. Early in the development cycle Spotify, Robinhood, and Slack engineers became adopters and contributors; without their help I wouldn’t be writing this blog post today 🙏. JP became a vocal champion of rules_xcodeproj after integrating it with the SwiftLint and Envoy Mobile projects. During BazelCon 2022 the project got a couple shout-outs, including during Erik’s wonderful talk. And I’m also incredibly grateful that I was able to present rules_xcodeproj itself at the same conference.

Deciding what was actually important for the 1.0 release shifted throughout the year. Some things that I initially thought were “nice to haves”, such as framework targets and comprehensive ruleset support, became “blockers” for the release. Other things that I was sure we would need before releasing, such as multiple Xcode configurations (e.g. Debug, Profile, and Release), diagnostic replaying, and BwX feature parity, ended up not being as important (though don’t worry if you are wanting some of those things, we aren’t done yet!).

The supported feature list also expanded throughout the year. It went from just needing to support the Core C/C++/Objective-C, rules_swift, and rules_apple rules, to supporting nearly any ruleset. Also, outside contributors made their mark: Chuck added support for custom Xcode schemes; Chirag added support for Runtime Sanitizers; Maxwell added support for Launch, Profile, and Test action environment variables and command-line arguments; Thi contributed BwB mode speed-ups and assisted with landing many more efficiency changes; and many others helped me test changes on their varied and complex projects. Overall these contributions, both in actual code and in invaluable time, allowed rules_xcodepoj to be what it is today. Without this community effort the scope and quality of the 1.0 release wouldn’t be at the same level.

What’s next?

While the 1.0 release marks a certain level “doneness”, there is still a lot we want to add and improve. When I announced rules_xcodeproj, I listed a set of requirements that other projects didn’t fulfill, and I stated that I wanted rules_xcodeproj to cover all of them. I feel that with the 1.0 release we still have a little ways to go to fully cover those requirements; though some will have to be in spirit instead of to the letter, as Bazel and Xcode proved to be more stubborn than I expected.

Here’s a list of changes that I hope we can implement in the near future:

  • An additional build mode, currently called “Build with Bazel via Proxy” (BwBvP)
    • Uses XCBBuildServiceProxyKit to create an XCBBuildService proxy
    • Adds replaying of diagnostics, which removes duplicate errors/warnings, persists warnings, and enables Fix-Its
    • Produces a custom Build Report, removing noise from the logs, and fixing the progress bar
  • BwB or BwBvP support for Xcode features that break with relative paths
    • Source code viewer in Instruments
    • Undefined Behavior Sanitizer navigation
    • Thread Performance Checker navigation
    • Memory Graph Analyzer with Malloc stack logging navigation
    • Inline code coverage
  • Support for multiple Xcode configurations

Thank you

Once again, I would like to thank all of the contributors and users we’ve gained throughout the last year. Hopefully you are as proud of the 1.0 release as I am. And for anyone reading that hasn’t tried rules_xcodeproj yet, or it didn’t meet your requirements in an earlier release, I invite you to give it a shot now.

If you run into any problems with rules_xcodeproj, please check if another issue already exists and comment on it, and if not, file an issue! You can also join us in the #rules_xcodeproj channel in the Bazel Slack workspace, and you can email us at with any questions, comments, or thoughts.