I have an app in the iPhone app store and have released several minor updates to it. I want to begin work on some major feature additions and reorganization, but don't want to lose the source code of my most recent version in case everything goes horribly wrong.

Should I start a new Xcode project from scratch and copy my existing source in? If I do this will I be able to submit the build from this new project as an update or will Apple complain that the build comes from a different Xcode project?

I've seen (but not used) Xcode's "Snapshots" and "Source Control" features - are these what I'm looking for?

Any help or direction greatly appreciated.