User Profile

I have downloaded an Objective-C Project CocoaSlideshow which I have modified, built, and run successfully in XCode 12.3 running on Catalina (10.15.7) but I cannot display the interface in XCode. I have created an archive and generated a .dmg file. There is no Main.storyboard file in the project. There is a message Unable to Load revisions at the bottom of the centre and right-hand panels. The Editor menu option does not include the option to display the Assistant Editor. How can I display the interface in this project?