---
title: HKMetadataKeyUDIDeviceIdentifier
framework: healthkit
role: symbol
role_heading: Global Variable
path: healthkit/hkmetadatakeyudideviceidentifier
---

# HKMetadataKeyUDIDeviceIdentifier

The device identifier portion of a device’s UDI (unique device identifier).

## Declaration

```swift
let HKMetadataKeyUDIDeviceIdentifier: String
```

## Discussion

Discussion The device identifier can be used to reference the GUDID (Globally Unique Device Identification Database). This key takes a string value. note: In iOS 9.0 and later, the use of this key is discouraged. Use the HKDevice class instead.

## See Also

### Device Information Keys

- [HKMetadataKeyDeviceSerialNumber](healthkit/hkmetadatakeydeviceserialnumber.md)
- [HKMetadataKeyUDIProductionIdentifier](healthkit/hkmetadatakeyudiproductionidentifier.md)
- [HKMetadataKeyDigitalSignature](healthkit/hkmetadatakeydigitalsignature.md)
- [HKMetadataKeyDeviceName](healthkit/hkmetadatakeydevicename.md)
- [HKMetadataKeyDeviceManufacturerName](healthkit/hkmetadatakeydevicemanufacturername.md)
- [HKMetadataKeyDevicePlacementSide](healthkit/hkmetadatakeydeviceplacementside.md)
- [HKDevicePlacementSide](healthkit/hkdeviceplacementside.md)
- [HKMetadataKeyAppleDeviceCalibrated](healthkit/hkmetadatakeyappledevicecalibrated.md)