iOS 3.x support in Xcode 4

Question

Is it possible to write apps that support iOS 3.x versions using Xcode 4? If so, how? And does Apple have any official recommendations on app backwards-compatibility?

Answer 1

to be sure, you can use Xcode 4 for targeting iOS 3.x as a deployment target, but you will not be able to simulate your program on a iOS 3.x SDK simulator. So you are pretty on your own (i.e., if you use any iOS 4.x-only feature, you will not find out it until you test on a physical device).

You need an older version of Xcode to debug against an older simulated SDK.