What's the cheapest way to filter a Core Data populated TableView with Sections?

Question

I've got a tableview populated by Core Data with multiple dynamic sections and I want to use a UISearchController to search for specific records. Every tutorial I've found says to use an array of fetched results, combined with a filtered array to display the results, but this is a pain for maintaining my tableview sections.

The code I have totally works, in that I just perform a fetch every time the user types in the search field, but I realize this is more expensive as far as resources go.

So how would I implement a filter on arrays while MAINTAINING my tableview sections? Arrays of arrays?

My current code:

//MARK: Search Deletegate Methods
func updateSearchResultsForSearchController(searchController: UISearchController) {
    let searchText = self.searchController.searchBar.text
    let selectedScopeButtonIndex = self.searchController.searchBar.selectedScopeButtonIndex
    self.filterContentForSearch(searchText, scope: selectedScopeButtonIndex)
    self.tableView.reloadData()

}


func filterContentForSearch(searchText: String, scope: Int)
{
    println("Fired")
    //Way too expensive for resources

    var fetchRequest = NSFetchRequest()
    fetchRequest = NSFetchRequest(entityName: "FoodItem")
    let sortDescriptor = NSSortDescriptor(key: "name", ascending: true)
    let mealDescriptor = NSSortDescriptor(key: "meal", ascending: true)
    fetchRequest.sortDescriptors = [mealDescriptor,sortDescriptor]
    //Predicate
    if searchText != ""
    {
    let namePredicate = NSPredicate(format: "name CONTAINS[cd] %@", searchText)
    fetchRequest.predicate = namePredicate
    }
    fetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: managedObjectContext, sectionNameKeyPath: "meal", cacheName: nil)
    fetchedResultsController.delegate = self
    fetchedResultsController.performFetch(nil)
}