Boutique is a project mainly written in PHP and OBJECTIVE-C, based on the View license.
Cocoa Boutique. In-app purchase system for Mac Cocoa apps
Cocoa Boutique is an open source framework that lets you add in-app purchase to your Mac Cocoa applications. Replacement for Kagi, eSellerate, Golden Braeburn etc
After taking your customers details in your own application, they are transmitted to your web server which calls PayPal's Website Payment Pro APIs. If the transaction is successful, it is recorded in your database and an AquaticPrime dictionary is transmitted back to your application on the customer's computer.
All configuration and response handling is setup by implementing the Cocoa Boutique delegate protocol.
Google Group - http://groups.google.com/group/cocoa-boutique
Twitter - @cocoaboutique