Xcode DerivedData and simulators

Xcode's build products (DerivedData) and the debug symbols it copies from every iPhone, Watch or Apple TV you connect (DeviceSupport) live in ~/Library/Developer/Xcode and can take 20–60 GB.

npx diskdiet scan --only xcode
npx diskdiet clean --only xcode

diskdiet removes DerivedData folders and DeviceSupport versions not changed for 30 days. Xcode rebuilds DerivedData on the next build and copies DeviceSupport again when you connect a device with that OS version. Archives are never touched: they're your builds for the App Store.

Simulators

npx diskdiet clean --only simulators

removes simulators for iOS, watchOS and tvOS versions that are no longer installed (diskdiet runs Xcode's own xcrun simctl delete unavailable) and simulator caches not used for 30 days. Simulators you can still run are never touched. To remove whole runtimes you no longer need, use Xcode → Settings → Platforms.

CocoaPods and Swift packages

npx diskdiet clean --only cocoapods,swiftpm

removes old pod versions from CocoaPods' download cache and old Swift Package Manager repositories and artifacts. Your projects' Pods folders and Package.resolved are never touched.