iPhone/ Xcode: Targeting the right iPhone OS's

Background: I have Xcode 3.2.3 installed and want to distribute a project, ideally to a variety of iPhone (iPod Touch?) devices, including ol开发者_运维百科der ones. When choosing Project -> Build -> Base SDK I'm seeing the options "iPhone Device 4.0" and "iPhone Device 3.2" (no more 3.1.x, though IIRC it was in in the previous version of Xcode, before I downloaded the latest one after iOS4).

Question: How can I set my deployment target to say iPhone OS 3.0 or 3.1? Or what should I do?

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Set the Base SDK to 4.0 and the Deployment Target to 3.0. As long as you don't use any of the new 4.0 functionality your app will run fine on a 3.0 device. Or get a copy of the 3.0/3.1 SDK (if you can find it, don't know if Apple keeps them around for download somewhere) and install it to a separate directory.