On my computer there's a folder of nearly 1GB in size at the following path:
/private/var/folders/ph/q7jl9fz115g104hfgpsw5k6w0000gn/C/com.apple.DeveloperTools/All/Xcode/EmbeddedAppDeltas
It remains there no matter whether I delete build folders or not. It appears to have every version of my app that I've ever archived in there. What's the purpose of that directory? I'd like to delete it as it's taking up over 900 MB, but I don't know what it's for, and googling did not help. Evidently they have it so well hidden that few people have noticed it before.
Best Answer
These apparently are temporary files associated with Xcode, but they don't seem to get cleaned up via a reboot. I followed the advice in this OSX Daily article and was able to clean up the folder by simply booting into safe mode. Just hold down shift while your computer is booting. Be prepared for it to take a few minutes. The folder was completely removed after safe booting.