Use when encountering BUILD FAILED, test crashes, simulator hangs, stale builds, zombie xcodebuild processes, "Unable to boot simulator", "No such module"…
Xcode Debugging Overview Check build environment BEFORE debugging code. Core principle 80% of "mysterious" Xcode issues are environment problems (stale Derived Data, stuck simulators, zombie processes), not code bugs. Example Prompts These are real questions developers ask that this skill is designed to answer: 1. "My build is failing with 'BUILD FAILED' but no error details. I haven't changed anything. What's going on?" → The skill shows environment-first diagnostics: check Derived Data, simulator states, and zombie processes before investigating code 2. "Tests passed yesterday with no code changes, but now they're failing. This is frustrating. How do I fix this?" → The skill explains stale Derived Data and intermittent failures, shows the 2-5 minute fix (clean Derived Data) 3. "My app builds fine but it's running the old code from before my changes. I restarted Xcode but it still happens." → The skill demonstrates that Derived Data caches old builds, shows how deletion forces a clean rebuild
don't have the plugin yet? install it then click "run inline in claude" again.