---
title: fileIdentifierKey
framework: foundation
role: symbol
role_heading: Type Property
path: foundation/urlresourcekey/fileidentifierkey
---

# fileIdentifierKey

The key for the file system’s internal inode identifier for the item.

## Declaration

```swift
static let fileIdentifierKey: URLResourceKey
```

## Discussion

Discussion The value associated with this key isn’t stable for all file systems or across all mounts. Use this value sparingly and don’t persist it. You can use it, for example, to match URLs from the URL enumerator with paths from FSEvents.

## See Also

### File keys

- [fileAllocatedSizeKey](foundation/urlresourcekey/fileallocatedsizekey.md)
- [fileProtectionKey](foundation/urlresourcekey/fileprotectionkey.md)
- [URLFileProtection](foundation/urlfileprotection.md)
- [fileContentIdentifierKey](foundation/urlresourcekey/filecontentidentifierkey.md)
- [fileResourceIdentifierKey](foundation/urlresourcekey/fileresourceidentifierkey.md)
- [fileResourceTypeKey](foundation/urlresourcekey/fileresourcetypekey.md)
- [URLFileResourceType](foundation/urlfileresourcetype.md)
- [fileSecurityKey](foundation/urlresourcekey/filesecuritykey.md)
- [fileSizeKey](foundation/urlresourcekey/filesizekey.md)
- [isAliasFileKey](foundation/urlresourcekey/isaliasfilekey.md)
- [isPackageKey](foundation/urlresourcekey/ispackagekey.md)
- [isRegularFileKey](foundation/urlresourcekey/isregularfilekey.md)
- [isPurgeableKey](foundation/urlresourcekey/ispurgeablekey.md)
- [isSparseKey](foundation/urlresourcekey/issparsekey.md)
- [mayHaveExtendedAttributesKey](foundation/urlresourcekey/mayhaveextendedattributeskey.md)