UX design has been getting pretty slick in the world of iOS. Last week, Facebook released Paper (subtitled “Stories from Facebook”), perhaps the best newsfeed app I have seen. This native iOS app is built using a toolkit called Origami that the Facebook design team has developed on top of Apple’s Quartz Composer for OSX and iOS. But even with the usability improvements introduced by Origami, Quartz Composer is still only a prototyping tool for iOS. You still need to know to write native iOS code (in this case UIKit) to implement the actual app.