---
title: clusterInitiatorAddress
framework: nearbyinteraction
role: symbol
role_heading: Instance Property
path: nearbyinteraction/nidltdoameasurement/clusterinitiatoraddress
---

# clusterInitiatorAddress

The address of the initiator anchor within the same cluster.

## Declaration

```swift
var clusterInitiatorAddress: Int { get }
```

## Discussion

Discussion In DL-TDOA deployments, anchors organize into clusters. An anchor cluster contains an initiator anchor and one or more responder anchors. The initiator coordinates a ranging sequence by sending an initial poll message. Use this property to group measurements from anchors that belong to the same cluster. Measurements with the same value for this property originate from anchors in the same cluster, even if their individual address differs. Group measurements by cluster To process measurements from related anchors together, group the measurements by cluster: func session(_ session: NISession, didUpdateDLTDOA measurements: [NIDLTDOAMeasurement]) {     // Group measurements by cluster.     let clusters = Dictionary(grouping: measurements) { $0.clusterInitiatorAddress }          for (initiatorAddress, clusterMeasurements) in clusters {         print("Cluster \(initiatorAddress) has \(clusterMeasurements.count) measurements.")         // Process measurements from this cluster together.         calculatePosition(from: clusterMeasurements)     } }

## See Also

### Identifying the anchor

- [address](nearbyinteraction/nidltdoameasurement/address.md)