add iPhone functionality to iPad app

I have been developing an iPad app. I now want to make it work开发者_如何学运维 on the iPhone also. What do I do in Xcode so it can work both ways?

(I am not concerned about adapting to the smaller screen -- that part I can figure out. But how do I get it to start up on the iPhone?)

In the project's build properties, change the target from "iPad" to "iPhone/iPad". Make sure you continue to target iOS 3.2, however, so that you don't break iPad support, and test on both platforms.