In the past I’ve mentioned some great libraries such as the excellent Magical Record providing active record for Core Data on the iOS platform.
Another tool that has been around for awhile is known as Mogenerator – what Mogenerator does is generate classes from your model and does so using a two class system with one class for machines, and one class for humans with all the necessary accessor and mutator methods.
The beauty of the dual class approach is that if you change your model you can update the machine class without messing up any of the work you’ve done.
You can download and read more about Mogenerator on the official page.
Rapture in Venice has created a good tutorial for getting started.
Definitely a time saving tool for anyone working with Core Data.
I highly suggest checking out the command line help when you get the tool to see everything you can do and this stack overflow provides a nice description of the Mogenerator command line parameters.