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  "identifier" : "/documentation/ARKit/ARSessionProviding/session",
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  "title" : "session"
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# session

A contract to declare an AR session.

```
var session: ARSession { get }
```

## Discussion

Some clients may use key-value observation (KVO) to be notified when this property changes values. To support KVO, Swift classes that adopt [`ARSessionProviding`](/documentation/ARKit/ARSessionProviding) should mark its [`session`](/documentation/ARKit/ARSessionProviding/session) as `@objc` and `dynamic`.

---

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