I need to support the following business scenario for managing updates:
App xxx.app(Version 6.1) is in the AppStore, it supports iOS 3 to 6.3.
We developed a new version xxx.app(Version 6.2) which supports iOS 7 and above.
Would it be possible to distribute an update for users of iOS 3 to 6.3, and another update for users of iOS 7 and above. (i.e something like two versions of one app)
I believe that is impossible. Here's why.
You can't do it if they are the same app. They are the same app if they have the same bundle id. So one solution would be to make this new version a different app. But that does not explain how you will update the old version. I doubt that Apple will let you submit an update today that does not run on iOS 8, or is not written with the latest version of Xcode. So you will never get your update to the old version into the App Store.
Perhaps a better way would be one app that runs on all systems with conditional code depending on what system it is. But that will be very difficult to write. The current version of Xcode cannot compile for such an early system.