iPhone - Add Core Data To existing Project?

Question

I am trying to add core data functionality to an existing project. I added a data model file named "myProj.xcdatamodel"

My code crashes in the following when getting the managedObjectModel What is the "momd" file? where can i get it or how can i create it? When i read the path it returns null and crashes the app.

NSString *modelPath = [[NSBundle mainBundle] pathForResource:@"myProj" ofType:@"momd"];
NSURL *modelURL = [NSURL fileURLWithPath:modelPath];

Answer 1

The momd file is the versioned equivalent of the mom file. You have two options at this point:

1. Add a version to your existing myProj.xcdatamodel model. In Xcode select the myProj.xcdatamodel file and select Design -> Data Model -> Add Model Version from the menu in Xcode.

2. Only use the non versioned model file. Change your supplied code to:

   NSString *modelPath = [[NSBundle mainBundle] pathForResource:@"myProj" ofType:@"mom"]; NSURL *modelURL = [NSURL fileURLWithPath:modelPath];

If you create a Navigation-based application (Use Core Data for storage) from the default template in Xcode, you'll notice the model file is already versioned.

For further information see: Model Versions