Used as a key in the user info dictionary passed to QTCaptureConnectionAttributeWillChangeNotification, and QTCaptureConnectionAttributeDidChangeNotification to indicate the key of that attribute that changed.
Available in Mac OS X v10.5 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)