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  "title" : "AudioAccessoryHeadTracking.Handler"
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# AudioAccessoryHeadTracking.Handler

```
protocol Handler : Sendable
```

## Topics

### Instance Methods

[`func activate(for: AudioAccessoryHeadTracking.Session)`](/documentation/AudioAccessoryKit/AudioAccessoryHeadTracking/Handler/activate(for:))

Called when a head-tracking session has been established with the host.

[`func handleAccessorySensorMessage(TransportMessage)`](/documentation/AudioAccessoryKit/AudioAccessoryHeadTracking/Handler/handleAccessorySensorMessage(_:))

Called when a `TransportMessage` arrives from the accessory’s
transport extension on the inbound channel.

[`func headTrackingStateDidChange(isActive: Bool)`](/documentation/AudioAccessoryKit/AudioAccessoryHeadTracking/Handler/headTrackingStateDidChange(isActive:))

Called when the user-facing Head Tracking state for this accessory
changes (e.g. via Settings or Control Center).

[`func invalidate()`](/documentation/AudioAccessoryKit/AudioAccessoryHeadTracking/Handler/invalidate())

Called when the head-tracking session has been invalidated.

## Relationships

### Inherits From

[`SendableMetatype`](/documentation/Swift/SendableMetatype)

[`Sendable`](/documentation/Swift/Sendable)

---

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