A card allows an app to export a screen to another app. Unlike an app that may offer a full and rich set of features, a card typically provides the ability to perform specific tasks such as picking a contact, composing an email, or previewing an image. To a user, a card appears as part of the client app and does not appear as a separate Active Frame.
Your app can export (or expose) a card, which makes it available for other apps to use. Your app can also import cards that other apps expose, which lets your app use the feature or functionality of those cards.
An app can expose only one card at a time. However, one card can expose another card, which allows the app to create a stack of cards that appear as part of the client app. Although the card appears as part of the client app, it maintains its own process and security context. In the following sections, you will learn how to create and use cards in your app, as well as how to expose them to other apps.
Last modified: 2015-03-31