NSDictionaryController with NSTableView and sorting of numeric data

FROM : jonathan@mugginsoft.com
DATE : Tue May 13 13:25:08 2008

Hello list

I have bound an NSDictionaryController to an NSTableView.
The keys in my bound dictionary are numeric strings 1... n
The dictionary keys and values display okay but the sorting of the key 
column is not numeric but alphabetic.
The value column sorts fine for objects of type NSNumber.
I have tried using NSNumber keys and an NSValueTransformer subclass 
but the controller seems to need an NSString key.

I know I am being dumb here. Please put me out of my misery.

Thanks

Jonathan