Question: I have a iPhone app and want to develop iPad app with the same name. I want to design different UI for ipad app including new features. So my question is, Will i have to make changes in iPhone app for iPad or need to create another new app for iPad ? Note: Name of both app will be same. Please explain how should i perform it.

Answer: 
What you describe is perfectly possible with [universal apps](http://developer.apple.com/library/ios/ipad/#documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/AdvancedAppTricks/AdvancedAppTricks.html). You will have to maintain to completely different hierachies of NIBs/Storyboards for your UI though. Controllers can be reused if you stick to the MVC pattern.
You can use same app for iPad but you have make different UI for iPad as size of iPhone and iPad screen is different but controllers and modal classes will remain same.