This repository provides an open-source Agent Skill designed to significantly improve Xcode build performance for iOS and macOS development teams. It addresses the common pain point of slow build loops by automating the process of benchmarking, analyzing, and optimizing clean and incremental builds, offering evidence-based improvements rather than guesswork. The target audience includes development teams struggling with build times, those investigating regressions, or anyone seeking a systematic approach to optimizing their Xcode build process.

How It Works

The system employs an orchestrator coordinating five specialist skills in a recommend-first workflow. Initially, the orchestrator benchmarks clean and incremental builds, then delegates analysis of compilation hotspots, project settings, and Swift Package Manager overhead to specialist skills. This culminates in a prioritized optimization plan generated at .build-benchmark/optimization-plan.md. Crucially, no project files are modified until the user explicitly reviews the plan and approves specific changes. A subsequent "fixer" skill applies only the approved modifications and re-benchmarks to verify improvements, ensuring a controlled and verifiable optimization process.

Quick Start & Requirements

Installation involves adding the skill via npx skills add https://github.com/avdlee/xcode-build-optimization-agent-skill. Usage requires an Xcode project opened within a compatible AI coding tool (e.g., Claude, Cursor, Codex-compatible). The primary interaction is via the /xcode-build-orchestrator skill. No specific hardware prerequisites beyond a standard development environment are mentioned, but build optimization inherently benefits from faster hardware.

Highlighted Details

• Performs over 40 individual checks across build settings, script phases, source code, and package dependencies.
• Analyzes compile hotspots, zero-change build overhead, target dependencies, Swift Package Manager graph, SwiftUI view decomposition, and more.
• Demonstrates significant real-world improvements, such as an 87% reduction in incremental build time for "Helm for App Store Connect" (70s to 9s) and a 32% improvement for "Stock Analyzer" (5.3s to 3.6s).
• Provides a shareable, diffable optimization plan (.build-benchmark/optimization-plan.md) for team review and auditing.

Maintenance & Community

The project is created by Antoine van der Lee, known for SwiftLee and RocketSim. Contributions are welcome following CONTRIBUTING.md guidelines. The repository focuses on Xcode build optimization within the Agent Skills framework.

Licensing & Compatibility

This repository is released under the MIT License, which is highly permissive and allows for commercial use, modification, and distribution with minimal restrictions. It is compatible with closed-source projects.

Limitations & Caveats

A small increase in clean build times may occur initially when enabling compilation caching, as the first build populates the cache. For long-term, continuous monitoring of build performance trends across teams and environments, the companion tool RocketSim is recommended. The skill's effectiveness is dependent on integration within supported AI coding environments.