Well, the guys from the mogenerator project have come up with a far superior solution in the mean time. The newest version of mogenerator comes with an Xcode plugin named Xmo’d, which monitors your *.xcdatamodel file for changes and, as soon as it changes, regenerates all of the neccessary files.

This means that there is officially no more reason not to use mogenerator.

To set it up, download the installer package from their (improved) project website and install it. (Before installing, please read the important release note about the renamed method +newInManagedObjectContext:.)

When installed, all you need to do is Command-click your *.xcdatamodel file, click Get Info, switch to the Comments tab and add the string “xmod” to the comment field. This is the trigger for Xmo’d to start (re)generating your machine-classes (the underscored class files) when the data model changes. Brilliant!

Oh, the default location at which the generated files will be emitted, is in a folder named after your project, right next to where your *.xcdatamodel already sits:

Enjoy it and spread the word!

Why is the deletion of a managed object from the NSManagedObjectContext so easy:

[context deleteObject:someObject];

Compared to its creation:

[NSEntityDescription insertNewObjectForEntityForName:@"someObjectClassName"
                              inManagedObjectContext:context];

Extending NSManagedObjectContext

Add the following category on NSManagedObjectContext to all of your Core Data projects and your pains will be history.

@implementation NSManagedObjectContext (NSManagedObjectContextConvenienceMethods)
 
- (id)newObject:(Class)entity {
    return [NSEntityDescription insertNewObjectForEntityForName:[entity description]
                                         inManagedObjectContext:self];
}
 
@end

Now, a call to create a new object is as easy as deleting it.

[context newObject:[someEntity class]];

Further enhancements of NSManagedObject

Matt Gallagher has written an excellent article about how to further enhance NSManagedObject for adding simple, one-line fetch support. Be sure to check it out.