---
title: volumeIdentifierKey
framework: foundation
role: symbol
role_heading: Type Property
path: foundation/urlresourcekey/volumeidentifierkey
---

# volumeIdentifierKey

The unique identifier of the resource’s volume, returned as an id (read-only).

## Declaration

```swift
static let volumeIdentifierKey: URLResourceKey
```

## Discussion

Discussion This identifier can be used with the isEqual(_:) method to determine whether two file system resources are on the same volume. The value of this identifier is not persistent across system restarts.

## See Also

### Volume support keys

- [isMountTriggerKey](foundation/urlresourcekey/ismounttriggerkey.md)
- [isVolumeKey](foundation/urlresourcekey/isvolumekey.md)
- [volumeCreationDateKey](foundation/urlresourcekey/volumecreationdatekey.md)
- [volumeLocalizedFormatDescriptionKey](foundation/urlresourcekey/volumelocalizedformatdescriptionkey.md)
- [volumeLocalizedNameKey](foundation/urlresourcekey/volumelocalizednamekey.md)
- [volumeMaximumFileSizeKey](foundation/urlresourcekey/volumemaximumfilesizekey.md)
- [volumeNameKey](foundation/urlresourcekey/volumenamekey.md)
- [volumeResourceCountKey](foundation/urlresourcekey/volumeresourcecountkey.md)
- [volumeSupportsAccessPermissionsKey](foundation/urlresourcekey/volumesupportsaccesspermissionskey.md)
- [volumeSupportsAdvisoryFileLockingKey](foundation/urlresourcekey/volumesupportsadvisoryfilelockingkey.md)
- [volumeSupportsCasePreservedNamesKey](foundation/urlresourcekey/volumesupportscasepreservednameskey.md)
- [volumeSupportsCaseSensitiveNamesKey](foundation/urlresourcekey/volumesupportscasesensitivenameskey.md)
- [volumeSupportsCompressionKey](foundation/urlresourcekey/volumesupportscompressionkey.md)
- [volumeSupportsExclusiveRenamingKey](foundation/urlresourcekey/volumesupportsexclusiverenamingkey.md)
- [volumeSupportsExtendedSecurityKey](foundation/urlresourcekey/volumesupportsextendedsecuritykey.md)