Why should we PHP warriors care at all about Apple's Passbook? Well first because Apple made this technology open (well, sort of…), second because it can be used outside iOS devices, and third because it involves a lot of well-known and loved technologies like JSON and RESTful APIs. I'd also add that it's a very interesting piece of technology, but that's my personal opinion. In this article I'll show you how I built a sample web application that creates and distributes passes in the form of a "PHPMaster Membership Card". It is not a full-featured product, but it's a nice base to build on for more serious real world uses.
He talks about the concept of a "pass" (a digitally signed document that can be easily distributed) and the types that the Apple service lets you make. His example (sample code here) is Silm based and Idorim & Paris for the data handling. He talks some about the certificate handling that's involved and the structure of the application including the certs, application code, templates and images. He then works through the code step-by-step and explains what each part does and how it connects with Apple's service to generate the pass.