Question

I’m using a secondary managedobjectcontext in a serial GCD queue, using the same persistent store coordinator (and model). The problem I am having is the secondary managedobjectmodel appears to be empty – all fetch requests return nothing. I am using a sqlite store. I’ve tried doing the same thing on the main thread to no avail.

The code is pretty straightforward. The CoreDataUtility is a singleton, and the manageObjectContext member of the singleton is the other managed object context.

    NSManagedObjectContext *managedObjectContext = [[NSManagedObjectContext alloc] init];
    [managedObjectContext setPersistentStoreCoordinator:[CoreDataUtility instance].managedObjectContext.persistentStoreCoordinator];

The fetch requests (I’ve tried several) are identical with the exception of the mom.

The secondary mom looks fine in the debugger – the properties you would expect to be the same in the primary mom are in fact the same.

Answer 1

The problem turned out to be with the way I was loading the model. I don’t have an explanation as to why this worked, but it did fix the problem. Maybe someone else can elucidate.

This code:

managedObjectModel = [[NSManagedObjectModel mergedModelFromBundles:nil] retain];

was replaced with this code:

NSString *modelPath = [[NSBundle mainBundle] pathForResource:@"mymodel" ofType:@"momd"];
NSURL *modelURL = [NSURL fileURLWithPath:modelPath];
managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];