Some files in my xcode project are referring to a viewcontroller that i probably made on the fly by exident and not the the one they should link to.
I got a viewcontroller called “StartViewController” when i try to import the StartViewController.h in xcodes the wrong one gets imported.

On the right you see the viewcontroller it should link to and on the left the viewcontroller that all other viewcontrollers are referring to for some reason
Backup the one you need, delete both from project and physically, then return backed up back and try to compile.