Xcode Not Immediately Recognizing New Classes (iOS)
Multiple Targets: Make sure your file belongs to the necessary targets!
For a new file, make sure the appropriate targets are checked.
For an existing file, check the file inspector to verify target membership.
Close all your projects, open the organizer (from the window menu), make sure the correct project is selected, then opposite 'derived data' click delete.
After that, close xcode, re-open it, open your project, clean it, and everything should work okay.