Pablo Defendini thinks this is interesting: Try creating a superclass called PrintedMaterials. Map out the properties that a class might have. Create classes for the other types of printed materials a store might carry. From Chapter 5: Object-Oriented Programming with Swift from Swift for Absolute Beginners by Brad Lees, Gary Bennett Publisher: Apress Released: December 2014 Note Done Share this highlight http://www.safaribooksonline.com/a/swift-for-absolute/108639/ Twitter Facebook Google Plus Email Get Instant Access Now Start a Free Trial Learn about Safari for Business Have an account? Sign in. Minimise Unlock the rest of Swift for Absolute Beginners and 30,000 other books and videos By clicking this box, you confirm that you have read and agree to the terms and conditions of our Membership Agreement, and you understand that when your trial period ends, you will be required to provide billing information if you wish to continue using the service. Unlock the rest of this book Start a Free 10-Day Trial loading Learn about Safari for Business Have an account? Sign in.