preservesVersions
A Boolean value that indicates whether the document subclass supports version management.
Declaration
class var preservesVersions: Bool { get }Return Value
true if the receiving subclass of NSDocument supports Versions; otherwise false.
Discussion
The default implementation of this method returns [self autosavesInPlace]. You can override it and return false to declare that NSDocument should not preserve old document versions.
Returning false from this method disables version browsing and revertToSaved(_:), which rely on version preservation when autosaving in place. Returning true from this method when autosavesInPlace returns false will result in undefined behavior.