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Alex Rupérez

Published: 22 Jul 15:19
I starred pinterest/xchammer at GitHub.
XCHammer generates Xcode projects from a Bazel Workspace.
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If all you've got is Xcode, your only tool is a 🔨

Build Status

XCHammer generates Xcode projects from a Bazel Workspace.

  • Complete Bazel Xcode IDE integration
    • Bazel build and run via Xcode
    • Xcode test runner integration
    • Full LLDB support without DSYM generation
    • Autocompletion and indexing support
    • Renders Bazel's progress in Xcode's progress bar
    • Optionally import index's via index-import with Run Scripts
    • Customize Bazel invocations for Xcode
  • Focused Xcode projects
  • Xcode build Bazel targets without Bazel
  • Optionally Bazel build Xcode projects
    • Define and compose Xcode projects in Skylark
    • Builds reproducible and remote cacheable projects
  • Automatically updates Xcode projects


Note: this README is intended to be a minimal, quick start guide. For a comprehensive explanation of XCHammer, see Introducing XCHammer and The XCHammer FAQ


Build and install to /usr/local/bin/

make install

Pinterest vendors for reproducibility and simplicity.


Generate using a XCHammerConfig.

xchammer generate <configPath>

Configuration Format

XCHammer is configured via a yaml representation of XCHammerConfig.

The configuration describes projects that should be generated.

# Generates a project containing the target ios-app
    - "//ios-app:ios-app"

            - "**"

See XCHammerConfig.swift for detailed documentation of the format.

To learn about how Pinterest uses XCHammer with Bazel locally check out Pinterest Xcode Focused Projects.


Bazel build Xcode projects

XCHammer additionally supports Bazel building Xcode projects, which enables remote caching and other features. This feature is experimental.

    name = "xchammer_resources",
    path = "/Path/To/",

# BUILD.Bazel
load("@xchammer_resources//:xcodeproject.bzl", "xcode_project")
    name = "MyProject",
    targets = [ "//ios-app:ios-app" ],
    paths = [ "**" ],

Xcode progress bar integration

XCHammer provides a path to optionally integrate with Xcode's build system and progress bar.

  • Install support for Xcode's progress bar for Xcode 11
xchammer install_xcode_build_system
  • add --build_event_binary_file=/tmp/bep.bep to your .bazelrc
  • make sure Xcode's new build system is enabled

LLDB integration

Under Swift and clang compilers, the execution root is written into debug info in object files by default. XCHammer writes an lldbinit file to map this directory to the source root of source code, so that both breakpoints and sources work in Xcode.

To make outputs consistent and debuggable across machines, e.g. with remote caching, it's recommended to use debug info remapping. Debug info remapping is a technique that simply remaps absolute paths in debug info to a stable location. LLDB then is able to map these to the source directory, via a target.source-map. By default, these Bazel flags are not configured and require adding additional flags to the build. Generally, these flags should set in your .bazelrc for every build.

Clang provides debug info remapping via the -fdebug-prefix-map flag. For Objective-C, C, C++, debug info remapping is implemented at the crosstool level. Configure Bazel to pass these arguments by setting --copt="DEBUG_PREFIX_MAP_PWD=." or providing a custom crosstool. See setting up crosstool logic for more info.

Starting with Xcode 10.2, Swift provides debug info remapping via the -debug-prefix-map flag. rules_swift supports the ability to pass the debug remapping. Simply add --swiftcopt=-Xwrapped-swift=-debug-prefix-pwd-is-dot to remap debug info in Swift.

XCHammer will automatically write a compatible remapping in the .lldbinit. Set HAMMER_USE_DEBUG_INFO_REMAPPING=YES via an xcconfig. See XCHammer's BUILD file, for an example of this.

Generating a dSYM for development is not recommended due to the performance hit, and in practice is only required for


Please find more info about developing XCHammer in The XCHammer FAQ. Pull requests welcome 💖.