How to increment variable in foreach loop

Hello people, 
for start sorry for my bad english, I'm french 

Someone can help for this : 

Code Block
import SwiftUI
struct requestFetch: View {
  @State private var somme: Double = 0
  @Environment(\.managedObjectContext) var managedObjectContext
  @FetchRequest(
    entity: Notes.entity(),
    sortDescriptors: [NSSortDescriptor(keyPath: \Notes.matiere, ascending: true)],
    predicate: NSPredicate(format: "matiere == %@", "Mathématique")
  )
  var note: FetchedResults<Notes>
   
  var body: some View {
    List(note) { not in
      somme = somme + 1
      Text("\(not.matiere!)")
    }
    Text("ok \(note.count)")
  }
}
struct requestFetch_Previews: PreviewProvider {
  static var previews: some View {
    requestFetch()
  }
}




This code doesn't work and I really need help 
It's somme = somme + not.note which don't work. 

Thanks for your help :)
How to increment variable in foreach loop
 
 
Q