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# join()

Starts the shared activity on the current device.

```
final func join()
```

## Discussion

Call this method to begin the delivery of synchronized data
to the current device. Typically, you call this method when your app
is ready to engage in an activity. For example, call it
when you present your app’s UI for the activity. When your app
successfully joins the session, the session changes the value in its
[`state`](/documentation/GroupActivities/GroupSession/state-swift.property) property to [`GroupSession.State.joined`](/documentation/GroupActivities/GroupSession/State-swift.enum/joined).

---

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