I’ve recently been battling with the problem of calculating the size of folders/files and have found a very nice chunk of code which works really well. So others don’t have to go to the trouble of re-writing this here is the link:

http://lists.apple.com/archives/carbon-dev/2005/Oct/msg01216.html

If only Apple would update NSFileManager to return the size of directories… Anyway, this works well.