Fastlane automates iOS build and deployment workflows. Install with gem install fastlane or Bundler. fastlane init sets up the initial configuration. Appfile stores Apple ID and team identifiers. Fastfile defines lanes for different workflows. match manages code signing with encrypted certificates. scan runs tests on simulator with configuration. gym builds the app with code signing. deliver uploads to App Store Connect. pilot manages TestFlight distribution. produce creates app records on App Store Connect. snapshot automates screenshot generation for multiple devices. frameit adds device frames to screenshots. prechecks verify build configuration before deployment. Increment build numbers automatically with increment_build_number. GitHub Actions integration triggers Fastlane on push. Configuration as code ensures reproducible builds. Environment variables manage sensitive credentials. Slack notifications inform team of build status. Fastlane reduces app store deployment to a single command. iOS CI/CD with Fastlane saves hours per release.