How to automatically setup Core Data relationship when using nested contexts

Question

I\'m struggling to figure out a decent solution to a problem that arises when using nested Managed Object Contexts in Core Data. Take a model that has two enites, Person and Nam

Answer 1

I ended up going with the convenience method solution. All the NSManagedObject subclasses in my app have a +insertInManagedObjectContext: method. Creating instances of those objects (in my own code) is always done using that method. Inside that method, I do this:

+ (instancetype)insertInManagedObjectContext:(NSManagedObjectContext *)moc
{
    MyManagedObject *result = [NSEntityDescription insertNewObjectForEntityForName:@"MyEntityName" inManagedObjectContext:moc]
    [result awakeFromCreation];
    return result;
}

- (void)awakeFromCreation
{
    // Do here what used to be done in -awakeFromInsert.
    // Set up default relationships, etc.
}

As for the NSArrayController issue, solving that isn't bad at all. I simply created a subclass of NSArrayController, overrode -newObject, and used that subclass for all the relevant NSArrayControllers in my app:

@implementation ORSManagedObjectsArrayController

- (id)newObject
{
    NSManagedObjectContext *moc = [self managedObjectContext];
    NSEntityDescription *entity = [NSEntityDescription entityForName:[self entityName]
                                              inManagedObjectContext:moc];
    if (!entity) return nil;

    Class class = NSClassFromString([entity managedObjectClassName]);
    return [class insertInManagedObjectContext:moc];
}

@end