Posted when the current progress of a running animation reaches one of its progress marks.
The notification object is a running NSAnimation object. The userInfo dictionary contains the current progress mark, accessed via the key NSAnimationProgressMark.
Available in Mac OS X v10.4 and later.
Declaration Syntax Version Information- Available in Monobjc Bridge: 10.6 (For Mac OS X 10.6 and later), 10.5 (For Mac OS X 10.5 and later)