TextFeild NSUndoManager

FROM : hac
DATE : Mon Apr 30 23:28:19 2007

In an app I'm making, there is a variety of filters wich the the user can
apply to a text feild. I'm having trouble getting the undo manager to
register the changes. I know this is fairly simple, but everything I try
doesn't work. Do I have to make an array of the text history? Any experience
would be great. Thanks.