coredata problem after changing property type

I had coredata working fine, until I needed to change 2 entitys from integer to string, now I get

The model used to open the store is incompatible with the one used to create the store

I tried deleting the app from the simulator, deleting the actual simulator file, deleting the build result, and changing the app name, to no avail,,, (I read somethin开发者_运维知识库g of deleting the xml, but cannot find it with the name of my app)

what to do please!!, I would not want to start over!! thanks

You need to delete the persistent store. It will be in your application support folder. If you're running in simulator, then i believe it is in the simulator's application support folder.

EDIT: The simulators application support folder is in

Library/Application Support/iPhone Simulator/

Poke around in there. You'll find what you're looking for.

Also, for ease of development with core data, sometimes what i do is delete the file when it fails to load. Make sure you post a log message so you know there was a loading issue. That way you won't have to manually delete the file whenever the store fails to load due to changes in the object model.