Method to change to NSFetchedResultsController dynamically

gistfile1.m

-(void)createFetchedResultsControllerWithSortOption:(NSInteger)sortOption animated:(BOOL)animated {
	self.fetchedResultsController.delegate = nil;
	self.fetchedResultsController = nil;
	[fetchedResultsController release];
	
	if (animated) {
		NSMutableIndexSet *sectionsToDelete = [[NSMutableIndexSet alloc] init];
		for (int i = 0; i < [self.tableView numberOfSections]; i ++) {
			[sectionsToDelete addIndex:i];
		}
		
		if ([sectionsToDelete count] > 0) {
			[self.tableView deleteSections:sectionsToDelete withRowAnimation:UITableViewRowAnimationLeft];
		}
		
		[sectionsToDelete release];
	}
	
	NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
	NSEntityDescription *entity = [NSEntityDescription entityForName:@"Person" inManagedObjectContext:managedObjectContext];
	[fetchRequest setEntity:entity];

	NSString *firstAttribute = nil;
	NSString *secondAttribute = nil;
	BOOL ascending = YES;
	NSString *cacheName = nil;
	BOOL hasSectionKey = YES;
	
	switch (sortOption) {
		case sortByDate: { // Working sort option
			
			firstAttribute = @"date";
			ascending = NO;
			cacheName = @"dateCache";
			hasSectionKey = NO;
			
		}
			break;
		case sortByName: { // Working sort option
			
			firstAttribute = @"name";
			cacheName = @"nameCache";
			hasSectionKey = NO;
			
		}
			break;
		case sortByCompany: { // Working sort option
			
			firstAttribute = @"company";
			secondAttribute = @"name";
			cacheName = @"companyCache";
			
		}
			break;
		case sortByJob: { // Broken sort option
			
			firstAttribute = @"job";
			secondAttribute = @"name";
			cacheName = @"jobCache";
			
		}
			break;
		case sortByRating: { // Working sort option
			
			firstAttribute = @"rating";
			secondAttribute = @"name";
			cacheName = @"ratingCache";			
						
		}
			break;
		case sortByLocation: { // Broken sort option
			
			firstAttribute = @"location";
			secondAttribute = @"company";
			cacheName = @"locationCache";
			
		}
			break;

	}
	
	NSMutableArray *sortDescriptors = [[NSMutableArray alloc] initWithCapacity:2];
	
	NSSortDescriptor *mainSortDescriptor = [[NSSortDescriptor alloc] initWithKey:firstAttribute ascending:ascending];
	
	[sortDescriptors addObject:mainSortDescriptor];
	[mainSortDescriptor release];
	
	if (secondAttribute != nil) {
		NSSortDescriptor *secondarySortDescriptor = [[NSSortDescriptor alloc] initWithKey:secondAttribute ascending:YES];
		[sortDescriptors addObject:secondarySortDescriptor];
		[secondarySortDescriptor release];
	}
	
	[fetchRequest setSortDescriptors:sortDescriptors];
	
	NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:managedObjectContext sectionNameKeyPath:(hasSectionKey) ? firstAttribute : nil cacheName:cacheName];
	self.fetchedResultsController = aFetchedResultsController;
	self.fetchedResultsController.delegate = self;
	
	[aFetchedResultsController release];
	[fetchRequest release];
	
	[sortDescriptors release];
	
	NSError *error;
	if (![[self fetchedResultsController] performFetch:&error]) {
		// Update to handle the error appropriately.
		NSLog(@"Fetch failed");
		NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
		exit(-1);  // Fail
	}
	if (animated) {
		NSMutableIndexSet *sectionsToInsert = [[NSMutableIndexSet alloc] init];

		for (NSUInteger i = 0; i < [[fetchedResultsController sections] count]; i ++) {
			[sectionsToInsert addIndex:i];
		}

		if ([sectionsToInsert count] > 0) {
			[self.tableView insertSections:sectionsToInsert withRowAnimation:UITableViewRowAnimationRight];
		}

		[sectionsToInsert release];
	} else {
		[self.tableView reloadData];
	}

}