ManagedObjectContext for Core Data Operations in Background thread.

- (NSManagedObjectContext*)getNewPrivateManagedObjectContext{
    NSManagedObjectContext *privateContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType];
    [privateContext performBlockAndWait:^{
        [privateContext setParentContext:self.managedObjectContext];
        [privateContext setMergePolicy:NSMergeByPropertyObjectTrumpMergePolicy];
        }];
    return privateContext ;
}

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