CoreData and Group By

Hi Folks,

Sorry I am sure this has been asked before - Beginner level programmer trying to get my head round something I am sure is simple. I know coredata is not a Relational database but please go easy!!

I have data my app is storing as people respond to the 'game'
a 'session' guid (runNumber) , and if they hit the correct button or not (correctAnswer). I want to group the responses by the guid and sum the 'correct' answers.

I think I am pulling the data correctly:

    @Environment(\.managedObjectContext) private var viewContext
    @FetchRequest(
        entity: CoreScore.entity(),
        sortDescriptors: [
            NSSortDescriptor(keyPath: \CoreScore.runNumber, ascending: false)
        ]
    ) var corescores: FetchedResults<CoreScore>


But my view

        List(corescores, id: \.self) { corescore in
            Text(corescore.runNumber ?? "Unknown")
            Text(corescore.correctAnswer ?? "Unknown")
        }

Shows all the individual responses...

How do I group them by runNumber?