Gets the file identifier for a PDF document.
- iOS 2.0+
- macOS 10.4+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 2.0+
- Core Graphics
The document whose file identifier you want to obtain.
Returns the file identifier for the document.
A PDF file identifier is defined in the PDF specification as an array of two strings, the first of which is a permanent identifier that doesn’t change even when the file is updated. The second string changes each time the file is updated. For more information, see PDF Reference: Version 1.3 (Second Edition), Adobe Systems Incorporated.