SharePlay
SharePlay is a technology to have apps on different devices stay in sync during a real-time session. The canonical example is two users watching the same movie while on a FaceTime call, but more people and more complex sharing scenarios are also supported.
This feature was first introduced in 2021 when many streaming apps had a “watch together” feature during Covid lockdowns.
Although SharePlay has dedicated support for syncing AVPlayers, developers can also sync custom content via a peer-to-peer connection, for example a drawing app that syncs drawing strokes. Users join a session and can change between activities in different apps. Apps can exchange messages via a reliable or unreliable channel (TCP/UDP), or sync files via an ad hoc shared storage mechanism.
WWDC 2021
Initial introduction of SharePlay, with support for creating a shared AVPlayer or sharing custom codable messages.
WWDC 2022
SharePlay sessions can now be started via iMessage, in addition to FaceTime. Message payload size expaned to 256KB.
WWDC 2023
SharePlay is available on visionOS with support for build-in spatial templates. Sessions can now be shared via AirDrop.
WWDC 2024
In visionOS, Personas in a SharePlay session can now be better placed using custom spatial templates. The Vision Pro Simulator adds support for simulated FaceTime calls.