A dictionary of arbitrary values associated with the receiver.
- iOS 7.0+
- macOS 10.9+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 2.0+
A KVO-compliant dictionary that changes in response to
set. The dictionary sends all of its KVO notifications on the thread that updates the property.
Some entries have meanings that are recognized by the
NSProgress class itself—see General progress user info dictionary keys, Progress kinds, File operation user info dictionary keys, and File operation kinds.