GroupActivities Reference

Signatures, availability, and deprecations for the GroupActivities framework — the SharePlay API. Every signature is verified against the iOS 27 SDK interface rather than the web documentation, which truncates several of these pages.

New to Axiom's SharePlay coverage? Start at the SharePlay overview.

When to Use This Reference

Use this reference when:

• You need an exact signature, and the rendered Apple page shows only a member list
• You're checking whether a symbol exists on a given platform or OS version
• You've inherited SharePlay code and need to know which APIs are deprecated
• You're auditing a switch over ActivityType or GroupSession.State
• You need to know which import an overlay symbol requires

Example Prompts

Questions you can ask Claude that will draw from this reference:

• "What's the full list of GroupActivityMetadata.ActivityType values?"
• "Is GroupActivityTransferRepresentation available on tvOS?"
• "What replaced metadata.localizedTitle?"
• "What are the cases of GroupActivityActivationResult and what should each one do?"
• "Which import do I need for GroupActivitySharingController?"

What's Covered

Setup

Entitlement, Info.plist requirements, allowed target types, platform support

Activity definition

GroupActivity, GroupActivityMetadata, ActivityType (all ten values), LifetimePolicy, SceneAssociationBehavior, BroadcastOptions

Activation and discovery

GroupStateObserver, GroupActivityActivationResult, prepareForActivation(), activate(), GroupActivitySharingController, GroupActivityTransferRepresentation

Session

GroupSession, GroupSession.State, GroupSession.Sessions, Participant, Participants

Distributed state

GroupSessionMessenger, DeliveryMode, Messages, MessageContext, GroupSessionJournal, Attachment, Attachments

Notices

GroupSessionEvent, Action, QueueChange

Migration

Full deprecation table, cross-import overlay requirements, visionOS availability matrix

Documentation Scope

This page documents the shareplay-ref skill in the axiom-integration suite. It is a lookup surface — patterns, decision-making, and the reasoning behind them live in the discipline skills.

• For discipline and patterns, see shareplay
• For coordinated media playback, see shareplay-playback

Notes That Change How You Write the Code

A few facts in this reference are load-bearing enough to call out, because the obvious reading of Apple's documentation produces working-looking code that is wrong.

ActivityType is a struct of static lets, not an enum. A switch over it needs default:. There are ten values; the deprecated Experience enum exposes only two of them.

GroupSession.State and GroupActivityActivationResult are non-frozen. In Swift 6 language mode, a switch without @unknown default is a compile error rather than a warning.

The journal has no pre-download validation hook. Attachments cap at 100 MB, and there is no point at which you can gate, moderate, or check entitlements before a participant downloads. Apple directs protected content to your own server.

activate() returns Bool, and false is a success — it means no session will be delivered to your app, so stop waiting rather than retrying or calling end(). An Apple TV handoff is one case where that happens, not the definition. Failure throws.

GroupActivityTransferRepresentation is unavailable on tvOS, even though GroupActivities itself runs there. The share-sheet, ShareLink, and AirDrop discovery paths simply don't exist on that platform.

GroupSession is not Sendable, while GroupSessionMessenger and GroupSessionJournal are @unchecked Sendable. Observation is Combine-only — there is no AsyncSequence for state, activity, or activeParticipants.

GroupSessionJournal.Attachments.Element is an array, not a single attachment. Each iteration delivers the entire current set to everyone, including whoever uploaded it.

Nothing in GroupActivities changed between the 26 and 27 SDKs on iOS or visionOS — no additions, no removals. Guidance here is stable across that boundary.

Resources

WWDC: 2021-10183, 2021-10187, 2022-10140, 2023-10239, 2023-10241

Docs: /groupactivities, /groupactivities/groupsession, /groupactivities/groupsessionmessenger, /groupactivities/groupsessionjournal, /groupactivities/groupactivitymetadata, /xcode/configuring-group-activities