Problem with bindings to user defaults

FROM : Bob Smith
DATE : Sun Apr 27 04:32:26 2008

I have an array of simple values, i.e. NSStrings or NSDates, and I 
want to store that array in user defaults.  I also want the array to 
be editable in the preferences UI.  I set up a single-column table 
and bind the table column to an NSArrayController instance that is 
bound to the desired key in the Shared Defaults controller.  The 
model property key in the table column binding is blank because the 
values are the actual objects in the array, not properties of those 
objects.  So far so good.

If the array already exists in user defaults and contains values, 
those initially appear in the table.  Using -add: and -remove: in the 
array controller will add and remove array values.  But the values 
can't be edited!  Any attempt to edit throws an exception about 
NSString, or NSDate, or whatever, not being key-value coding 
compliant for "" (an empty key).  The table, or maybe the array 
controller, doesn't seem able to simply replace the value object in 
the array, it just tries to set a new value for a key in that object, 
even though no key was given.  Yet the table/controller had no 
trouble loading pre-existing values correctly for initial display, 
despite not having a property key.

Am I doing something wrong when setting up the bindings?  Is there 
some other way to edit a list of values without using a table?  Is 
this just a limitation in bindings to a table?  I've been through the 
docs and examples but never found any clues.  I've run into this a 
couple of times now, and always just ended up building a temporary 
model of "wrapper" objects for the table binding, with controller 
code to move values in and out of user defaults.  Not really a lot of 
code to write, but it seems like this should be a no-code-required 
task.  I suspect I am missing something really obvious, but I'm quite 
happy to feel dumb if someone can point out my error.

Thanks!

Bob