Usually Cmd + Shift + K will do a clean but if not, the derived data is in
~/Library/Develop/Xcode/DerivedData
cd
into that directory and do rm -r [directory name]
Dev Notebook
Usually Cmd + Shift + K will do a clean but if not, the derived data is in
~/Library/Develop/Xcode/DerivedData
cd
into that directory and do rm -r [directory name]