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# session(_:didUpdateDLTDOA:)

Provides device ranging estimates for a Downlink Time-Difference-of-Arrival session.

```
optional func session(_ session: NISession, didUpdateDLTDOA measurements: [NIDLTDOAMeasurement])
```

## Parameters

`session`

The session that provides a Downlink Time-Difference-of-Arrival measurement.

`measurements`

The measurement updates for the session.

## Discussion

The framework invokes this callback to provide measurements for sessions that run [`NIDLTDOAConfiguration`](/documentation/NearbyInteraction/NIDLTDOAConfiguration).

---

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