[App Extensions](🔗) in iOS are an important component of the iOS ecosystem that are supported by RevenueCat. The most popular use of App Extensions for subscription apps are Today Widgets and iMessage apps.
# Configuring for App Extensions
To enable data sharing between the main app and extensions, you'll need to use Xcode or the Developer portal to [enable app groups for the containing app and its contained app extensions](🔗). Then, [register the app group in the portal](🔗) and specify the app group to use in the containing app.
After you enable app groups, you will be able to access a user's active subscriptions in your App Extension by configuring _Purchases_ with a custom UserDefaults that's shared across your App Extension.
Now the app extension and parent app can both use the a shared UserDefaults suite.