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# dataServiceIdentifierDidChange(_:)

Informs the delegate when the identifier changes for the service that’s currently providing data.

```
optional func dataServiceIdentifierDidChange(_ identifier: String)
```

## Parameters

`identifier`

The identifier of the service that’s currently providing data. Use this identifier as the key in [`serviceCurrentRadioAccessTechnology`](/documentation/CoreTelephony/CTTelephonyNetworkInfo/serviceCurrentRadioAccessTechnology) to get the value of the new radio access technology for the service.

---

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