How to build against older iOS versions with the latest Xcode downloads?

Question

I have multiple versions of Xcode installed. I can build my project against older iOS versions by launching old Xcode. But how could I use newer Xcode versions to build agai

Answer 1

To make an application target that runs on multiple versions of iOS is relatively simple: Set the “Base SDK” in your projects settings to the newest version number of iOS whose features you may want. Set the “iPhone OS Deployment Target” to the oldest version number of iOS that you will support

you will need to install older versions of xcode since the newer simulator will only support the newer ios versions

http://developer.apple.com/library/mac/#documentation/Xcode/Conceptual/XcodeCoexistence/Contents/Resources/en.lproj/Details/Details.html