What Does Question Mark Mean in Xcode Project Navigator?

Question

In the project navigator in Xcode, I am not sure what the ? is trying to tell me next to the file name.

I am sure it is not a coincidence that this is the same file that I dragged from my root directory for the project to the Classes folder (because the .mm file was there and I wanted them to be together). The project still compiles just fine, however my code sense broke recently and I am wondering whether this may be part of the issue.

Thanks!

Answer 1

It's the file untracked by source control.