.XCODEPROJ File Extension
What is an XCODEPROJ file?
XCODEPROJ files include links to source code files (sources), docs, resources, frameworks, libraries, and products. They also store targets, executables, find results, bookmarks, project symbols, and links to implementation files and interface builder (NIB) files.
To create an XCODEPROJ file with Xcode, select File → New → Project.... After saving a project as an XCODEPROJ file you can close it, then re-open it for further editing.
NOTE: When you are finished developing the project saved in the XCODEPROJ file you can build the project data into an executable app with Xcode that can be distributed.
How to open an XCODEPROJ file
You can only open XCODEPROJ files with Apple Xcode in macOS. To open the file, select File → Open....