Messaging and VoIP Apps
Messaging and VoIP apps use Siri and are exclusively voice-driven. They don’t present interfaces to the user, so no interface design is necessary that’s specific to CarPlay.
Support both reading and composing messages. A messaging app optimized for CarPlay must allow the user to read and compose messages using only their voice.
Enable CarPlay notifications. A messaging app must explicitly opt in for its notifications to appear in CarPlay. For developer guidance, see UNNotificationCategoryOptionAllowInCarPlay.
Display only message notifications. Categorize your messaging notifications in a way that segregates them from other types of notifications.
Enable the appropriate Siri functions if your app supports VoIP. To work with CarPlay, a VoIP app must allow the user to search the call history and start audio calls using Siri. For developer guidance, see INSearchCallHistoryIntentIdentifier, and INStartAudioCallIntentIdentifier.
For developer guidance, see SiriKit Programming Guide.