gistfile1.m

    //Access the oppropriate entity 
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Task" inManagedObjectContext:((AppDelegate *)[[UIApplication sharedApplication]delegate]).managedObjectContext];
    
    //Creating a child context to use in the background thread
    NSManagedObjectContext *context = [[NSManagedObjectContext alloc]initWithConcurrencyType:NSPrivateQueueConcurrencyType];
    
    //Setting the parent context
    context.parentContext = ((AppDelegate *)[[UIApplication sharedApplication]delegate]).managedObjectContext;
    
    //Call fetching in background 
    [context performBlock:^{
    
        NSFetchRequest *request = [[NSFetchRequest alloc]init];
        
        //Setting the entity (table) to be fetched
        [request setEntity:entity];
        
        NSError *error = nil;
        
        //Array pupulated with the objects
        NSMutableArray *resultsArray = [[NSMutableArray alloc]initWithArray:[context executeFetchRequest:request error:&error]];
        
        }