Delete all objetcts in a MOC

delete-all-objects.m

    NSArray *entities = self.managedObjectContext.persistentStoreCoordinator.managedObjectModel.entities;

    for (NSEntityDescription *desc in entities)
    {
        NSFetchRequest *allObjectsRequest = [NSFetchRequest fetchRequestWithEntityName:desc.name];

        NSError *fetchError;
        NSArray *allObjects = [self.managedObjectContext executeFetchRequest:allObjectsRequest error:&fetchError];
        if (allObjects)
        {
            for (NSManagedObject *obj in allObjects)
            {
                [obj.managedObjectContext deleteObject:obj];
            }
        }
    }

    [self.managedObjectContext saveChanges];