How to use SharePlay via Messages on iPhone | Apple Support

You can use SharePlay to watch a movie or listen to music with friends while chatting in Messages. First, touch and hold the content in a supported app or tap the more button, then tap SharePlay. Add your contacts, tap the Messages button, enter a message, and send the invitation. Once your contacts join, tap Start to begin playing. Tap the Messages button to return to chatting. While listening and chatting, you can access playback controls by touching and holding the dynamic Island. To end the session, tap the X in the SharePlay controls. This keeps everyone in sync with SharePlay.

Summary:
– Use SharePlay to watch movies or listen to music with friends while chatting in Messages.
– Touch and hold the content in a supported app, tap the more button, then tap SharePlay.
– Add contacts, tap Messages, enter a message, and send the invitation.
– Once contacts join, tap Start to begin playback and return to Messages for chatting.
– Access playback controls by touching and holding the dynamic Island; end the session by tapping the X in the SharePlay controls.