---
title: "updateMotionState(_:forObjectWithToken:)"
framework: nearbyinteraction
role: symbol
role_heading: Instance Method
path: "nearbyinteraction/nisession/updatemotionstate(_:forobjectwithtoken:)"
---

# updateMotionState(_:forObjectWithToken:)

Notifies the session of an accessory’s motion state change.

## Declaration

```swift
func updateMotionState(_ motionState: NIMotionActivityState, forObjectWithToken token: NIDiscoveryToken)
```

## Parameters

- `motionState`: The current motion state of the accessory.
- `token`: The discovery token that identifies the nearby accessory.

## Discussion

Discussion Ranging accuracy improves when the framework knows whether the accessory is moving. Track your accessory’s motion using a method you choose and then describe the motion with the appropriate NIMotionActivityState. Call this method, providing the motion state, when the accessory’s motion state changes: func handleMotionStateUpdate(_ state: NIMotionActivityState, session: NISession) {     guard let config = session.configuration as? NINearbyAccessoryConfiguration else {         return     }     session.updateMotionState(state, forObjectWithToken: config.accessoryDiscoveryToken) } This method works with NINearbyAccessoryConfiguration sessions, and applies to Ultra Wideband and Bluetooth Channel Sounding sessions.

## See Also

### Providing accessory state information

- [NIMotionActivityState](nearbyinteraction/nimotionactivitystate.md)