<!--
{
  "availability" : [
    "iOS: 11.0.0 -",
    "iPadOS: 11.0.0 -",
    "visionOS: 1.0.0 - 1.0.0"
  ],
  "documentType" : "symbol",
  "framework" : "ARKit",
  "identifier" : "/documentation/ARKit/ARSessionObserver",
  "metadataVersion" : "0.1.0",
  "role" : "Protocol",
  "symbol" : {
    "kind" : "Protocol",
    "modules" : [
      "ARKit"
    ],
    "preciseIdentifier" : "c:objc(pl)ARSessionObserver"
  },
  "title" : "ARSessionObserver"
}
-->

# ARSessionObserver

Methods you can implement to respond to changes in the state of an AR session.

```
protocol ARSessionObserver : NSObjectProtocol
```

## Overview

This protocol defines optional methods common to the [`ARSessionDelegate`](/documentation/ARKit/ARSessionDelegate), [`ARSCNViewDelegate`](/documentation/ARKit/ARSCNViewDelegate), and [`ARSKViewDelegate`](/documentation/ARKit/ARSKViewDelegate) protocols. You can implement this protocol’s methods when adopting one of those protocols.

## Topics

### Responding to Tracking Quality Changes

[`-  session:cameraDidChangeTrackingState:`](/documentation/ARKit/ARSessionObserver/session(_:cameraDidChangeTrackingState:))

Informs the delegate of changes to the quality of ARKit’s device position tracking.

[`-  session:didChangeGeoTrackingStatus:`](/documentation/ARKit/ARSessionObserver/session(_:didChange:))

Listen and react to geo-tracking state changes.

### Handling Interruptions

[`-  sessionWasInterrupted:`](/documentation/ARKit/ARSessionObserver/sessionWasInterrupted(_:))

Tells the delegate that the session has temporarily stopped processing frames and tracking device position.

[`-  sessionInterruptionEnded:`](/documentation/ARKit/ARSessionObserver/sessionInterruptionEnded(_:))

Tells the delegate that the session has resumed processing frames and tracking device position.

[`-  sessionShouldAttemptRelocalization:`](/documentation/ARKit/ARSessionObserver/sessionShouldAttemptRelocalization(_:))

Asks the delegate whether to attempt recovery of world-tracking state after an interruption.

### Receiving Audio Data

[`-  session:didOutputAudioSampleBuffer:`](/documentation/ARKit/ARSessionObserver/session(_:didOutputAudioSampleBuffer:))

Tells the delegate that a new sample buffer of recorded audio is available.

### Handling Errors

[`-  session:didFailWithError:`](/documentation/ARKit/ARSessionObserver/session(_:didFailWithError:))

Tells the delegate that the session has stopped running due to an error.

[`ARErrorDomain`](/documentation/ARKit/ARErrorDomain)

The domain for error objects produced by an AR session.

### Managing Collaboration

[`-  session:didOutputCollaborationData:`](/documentation/ARKit/ARSessionObserver/session(_:didOutputCollaborationData:))

Provides information for nearby users about your perspective in the environment.

## Relationships

### Inherited By

[`ARSKViewDelegate`](/documentation/ARKit/ARSKViewDelegate)

[`ARSCNViewDelegate`](/documentation/ARKit/ARSCNViewDelegate)

[`ARSessionDelegate`](/documentation/ARKit/ARSessionDelegate)

### Inherits From

[`NSObjectProtocol`](/documentation/ObjectiveC/NSObjectProtocol)

---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)