SWIFTUI Core Data Object Return from Picker

Code Block 
import SwiftUI
import CoreData
struct ContentView: View {
    @FetchRequest private var players: FetchedResults<Player>
    @State private var selection: Player
    init(moc: NSManagedObjectContext) {
        let fetchRequest: NSFetchRequest<Player> = Player.fetchRequest()
        fetchRequest.sortDescriptors = [NSSortDescriptor(keyPath: \Player.familyName, ascending: true)]
        fetchRequest.predicate = NSPredicate(value: true)
        self._players = FetchRequest(fetchRequest: fetchRequest)
        do {
            let firstPlayer = try moc.fetch(fetchRequest)
            self._selection = State(initialValue: firstPlayer[0])
        } catch {
            fatalError("Uh, fetch problem...")
        }
    }
    var body: some View {
        VStack{
            Picker("", selection: $selection){
                ForEach(players) { (player: Player) in
                    Text(player.givenName ?? "")
                        .tag(player)
                }
            }
            Text(selection.familyName ?? "No family name")
            Text("\(players.count)")
        }
    }
}

Preamble

The solutions previously posted don't allow for the picker to initially have no value selected, but sometimes you may want this. Going with the code-example in the Original Poster's question above, let's say the Original Poster wished to initially have no player selected in the Picker, in which case "default" would be shown in the first Text View until the first time the user selects a Player via the Picker View.

Problem

The tag type doesn't match that of selection.

Solution

Cast the player to Player? in the .tag(...) View Method call, so that the tag's type will match that of selection/$selection.wrappedValue.

Here's the Original Poster's code-example with this solution applied:

struct TestView: View {
  @Environment(\.managedObjectContext) var viewContext
  @FetchRequest(
    sortDescriptors: [NSSortDescriptor(keyPath: \Player.familyName, ascending: true)],
    animation: .default)
  private var players: FetchedResults<Player>
   
  @State var selection: Player?
   
  var body: some View {
    VStack{
      Picker("", selection: $selection){
        ForEach(players, id: \.self){ (player: Player) in
          Text(player.givenName!).tag(player as Player?) // Cast `player` to `Player?`, so that the tag's type will match that of `selection`.
        }
      }
      Text(((selection?.familyName ?? "default")))
      Text("\(players.count)")
    }
  }
}