Are they backed up?
I'd delete via the Finder, yes. I'd do that, and empty the trash, w/Xcode closed, just to be safe on that level.
Try the empty dirs first, then see if your Xcode complains about it going away, but I don't believe there is any issue, it's not like separate resources are in play.
I do think they come in handy if you need to debug crashes later, tho. I just keep them -and- back them up.
Yes I did back them up. Deleting the archives and the empty folders didn't cause any problems for Xcode. The bad news is, Organizer still displays all of the empty projects.
Several years ago I was invited to the development team of a large organization that has about 900 apps. At the time, the person who invited me didn't know how to invite me to just the apps I needed to work on, so I ended up having access to all 900 apps, and somehow at some point Xcode ended up showing all of those apps in my Organizer view, even though I never built them or even had the project files. To this day I still see them there and can't find a way to get rid of them. I even asked the manager of the organization to remove my access to those projects, which he did. It's not a huge problem, but I'd like to clean it up. Any idea where Organizer is getting that list from?
I think typically Xcode maintains such 'lists' via it's plist prefs in ~/Library/Preferences ...seen those before?
Maybe you can open them in a text editor just to take a peek.
If you wipe them out, Xcode builds new ones the next time it runs.
I found the list in ~/Library/Developer/Xcode/Products as a series of directories. It looks like I'll need to manually delete the ones I don't need as there is no easy way to distinguish them from the active ones, but that's better than nothing.