How it works…

The following diagram describes how Passes are delivered to a Passbook, and how these can be updated:

The process of creating a Pass involves cryptographically signing the Pass using a certificate and key generated from your iOS developer account. For this reason, the generation of the Pass needs to take place on a server, and then be delivered to Passbook either via your own app, as an e-mail attachment, or by embedding it in a website.

It's important to note that Apple does not provide any system for the Pass providers to authenticate, validate, or invalidate Passes. The Pass can contain barcode information, but it is up to the Pass provider to provide the infrastructure for reading and processing these barcodes.

Instead of just sitting in the Passbook app, waiting to be used, a Pass can contain location and time triggers, that proactively present the Pass to the user, serving as both a reminder and providing convenient access. For example, an event Pass could be set to appear 15 minutes before the start time, at the time when a user is likely to want to present their event Pass to an attendant. Alternatively, a coupon Pass could be presented as a user approaches their local store where the coupon can be redeemed.

Passes that have been added to Passbook can also be updated dynamically. For example, if the Pass is for a store card, a change to the card balance may require an update to the Pass. In the case of, for example an airline ticket Pass, a departure gate change should trigger a Pass update.

When a Pass needs to be updated, your server sends a push notification to the Passbook app on the user's device. This push notification is not displayed to the user.

Upon receiving this Push Notification, the Passbook app then makes a request to your server for the updated Pass information. Your server would then respond to the relevant request, and provide the updated information in the expected format.

When the Passbook App on the user's device receives the updated information, it silently updates the Pass. The next time the user looks at the Pass contained in the Passbook app, the updated information is displayed.