# QLThumbnailRequestCopyURL(_:) Returns the URL of the document for which the thumbnail request is requested. ``` func QLThumbnailRequestCopyURL(_ thumbnail: QLThumbnailRequest!) -> Unmanaged! ``` ## Parameters `thumbnail` The thumbnail request object. ## Return Value The URL identifying the document for which the thumbnail is requested. You should explicitly release the CFURL object when it is no longer needed. ## Discussion Thread-safety: This function should be called in the same thread as the thumbnail request is made in; generally, this is the same thread in which the `GenerateThumbnailForURL` callback was invoked. --- 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)