# fileReferenceURL() Returns a new file reference URL that points to the same resource as the receiver. ``` func fileReferenceURL() -> URL? ``` ## Return Value The new file reference URL. ## Discussion File reference URLs use a URL path syntax that identifies a file system object by reference, not by path. This form of file URL remains valid when the file system path of the URL’s underlying resource changes. If the original URL is a file path URL, this property contains a copy of the URL converted into a file reference URL. If the original URL is a file reference URL, this property contains the original. If the original URL is not a file URL, this property contains `nil`. File reference URLs cannot be created to file system objects which do not exist or are not reachable. This property contains `nil` instead. In some areas of the file system hierarchy, file reference URLs cannot be generated to the leaf node of the URL path. > Important: > A file reference URL’s path should never be persistently stored, because it is not valid across system restarts or remounts of volumes. If you need to store a persistent reference to a file system object, use a bookmark instead. You can create a bookmark by calling ``doc://com.apple.foundation/documentation/Foundation/NSURL/bookmarkData(options:includingResourceValuesForKeys:relativeTo:)``. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)