how to change the base sdk to 3.0

I developed a project for the base sdk 3.0 and now I have installed xcode3.2.3. Now when I am trying to build my project it says missing sdk 3.0. And when I am trying to set the base sdk from the project settings there is no 3.0 sdk available in the list. Only 4.0 is available. So my que开发者_JAVA百科stion is how can I add 3.0 sdk in the new xcode version?

Thanks in advance.

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You can't do that with new XCode, but you can build with 4.0 as Base SDK and set "iPhone OS deployment target" in your target settings to the lowest OS version you want to support.