How can I convert an iPad only app into a Univeral app?

I recently wrote an iPad app that I would like to make a universal app.

What is the best way to do this? Can I simply create two versions of my XIB files and load the approp开发者_运维知识库riate XIB based upon the device?

This should help you out a lot: http://iphonedevelopment.blogspot.com/2010/04/converting-iphone-apps-to-universal.html

Yes, you can create 2 xib files for every screen (one for iPad, and one for iPhone/iPod).

Yes, you do need 2 .xib files for every screen. The tutorial that NeilMonday posted is helpful, but I found this one to be better: http://www.raywenderlich.com/1111/how-to-port-an-iphone-application-to-the-ipad