Xcode Build Baseline

Measure before recommending build-time changes. Do not edit project files while benchmarking.

Rules

• Keep workspace/project, scheme, configuration, destination, DerivedData path, and warm-up rules consistent.
• Capture clean and incremental behavior separately.
• Write timestamped JSON artifacts under .build-benchmark/.
• Report medians and spread, not only the fastest run.
• For iOS Simulator, resolve an installed iPhone/iOS pair; prefer OS=latest only when Xcode accepts it.
• In git worktrees, create missing package exclude: directories such as __Snapshots__ before dependency resolution, or SPM can crash.

Inputs

Infer or ask for workspace/project, scheme, configuration, destination, simulator/device preference, custom DerivedData needs, and a representative Swift file for incremental touch tests.

Default Run

1. Normalize the build command and record every cache-affecting flag.
2. Warm up once only if needed to prove the command succeeds.
3. Run 3 clean builds.
4. If COMPILATION_CACHE_ENABLE_CACHING = YES, run 3 cached-clean builds; use --no-cached-clean only when intentionally skipped.
5. Run 3 zero-change builds with no --touch-file; this measures fixed overhead from dependency planning, scripts, codesign, validation, and related phases.
6. Optionally run 3 incremental builds with --touch-file path/to/SomeFile.swift.
7. Preserve raw logs, summaries, and JSON artifacts.

Preferred helper:

python3 ../../shared/build-optimization/scripts/benchmark_builds.py \
  --workspace App.xcworkspace \
  --scheme MyApp \
  --configuration Debug \
  --destination "platform=iOS Simulator,name=<latest available iPhone simulator>,OS=latest" \
  --output-dir .build-benchmark

If the helper is unavailable, run equivalent xcodebuild commands with -showBuildTimingSummary and keep raw output.

Output

Return clean, cached-clean when enabled, zero-change, and touched-incremental medians/min/max; biggest timing categories; environment details; artifact path; and noise caveats.

If the user only requested measurement, stop there. For optimization, hand the artifact to the relevant skill: xcode-compile-profiler, xcode-project-auditor, swiftpm-build-inspector, or xcode-build-strategist.

Resources

• references/benchmarking-workflow.md
• ../../shared/build-optimization/references/benchmark-artifacts.md
• ../../shared/build-optimization/schemas/build-benchmark.schema.json