I've read up on how one can create a single iOS binary that combines an iPad and iPhone into a single (Universal) binary. However, I have not been able to figure out from this process whether it's feasible (or even advisable) to combine two different versions of the same iPhone app into a single binary.
The reason that I would like to do this is that I have done a full refactoring of my app to take advantage of iOS 5 features, etc. When I first began this, I figured the finished product would be released and I would stop support iOS 4. What I have realized in the interim is that there are still some people who use earlier iOS versions. I don't want to prevent them from downloading the app in the future. Ideally I would distribute a binary that (at runtime) determines which version of iOS is running and then load the appropriate bundled version of the app.
I have seen some jailbreak trickery (launch shell scripts) to accomplish this sort of thing, but no non-jailbreak examples. Any insight would be appreciated.
Thanks, Chris