Change build with iOS 4.0.1

Hey, Am writing an iOS application a开发者_Python百科nd want to build it so it will run in iOS version 4.0.1 or later however the only SDK I have installed is iOS 4.2 and am unable to select an earlier version. Does anyone know how I change it so that I can build against earlier versions?

Thanks, William

You always want to build with the latest SDK, to change which devices you can deploy to simply alter the "ios deployment target" on the project properties to iOS 4.0 or similar