The identifier for this version of the file.
- iOS 5.0+
- macOS 10.7+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 2.0+
You can save the value of this property persistently and use it to recreate the version object later. When recreating the version object using the
version(item method, the version object returned is equivalent to the current object.