I was working on my project and suddenly after editing the code and compiling gave this error:
ld: warning: directory not found for option \'-
L/Use
If this happens to you with CoreData generated classes, combine the +CoreDataProperties and +CoreDataClass into the +CoreDataProperties class and delete the +CoreDataClass. Make sure to search Derived Data for leftovers of the +CoreDataClass. Even after deleting the Derived Data and cleaning I sometimes had Xcode just generate the +CoreDataClass again and again. Deleting it manually in Finder and then re-bulding helped me solve this.