What is the little arrow pointing to .swift files in my Xcode project?

In my project some of the code files have a small arrow pointing to the swift icon on the lower left corner. I searched Apple's Xcode docs and tried Google searches by text and also by image, but came up empty. Any idea what this is trying to tell me?

I looked at the files in the Finder to see if they were aliases, but they are not.

That little arrow in the icon is Xcode's way of telling you that the file's path on the file system does not match the file's location within the project.

Select the file in Xcode. Display the File Inspector on the right side of Xcode. Between the Location dropdown and the Full Path value you will see a filename or a relative path and filename. Files with just a filename do not have the little arrow in their icon. Files that show a relative path are the files that do have the little arrow in their icon.