Using IdentifiedCollection package to manage large lists in SwiftUI

DemoLister.swift

//
//  ContentView.swift
//  DemoLister
//
//  Created by Ray Fix on 12/11/21.
//

import SwiftUI
import IdentifiedCollections

struct Todo: Identifiable {
  var id: UUID
  var name: String
  var isCompleted: Bool
}

final class ViewModel: ObservableObject {
  @Published var items: IdentifiedArrayOf<Todo>
  
  init(count: Int) {
    self.items = IdentifiedArrayOf<Todo>(uniqueElements:
      (1...count).map {
        Todo(id: UUID(), name: "Item \($0)", isCompleted: .random())
      })
  }
  
  func toggleComplete(id: UUID) {
    items[id: id]?.isCompleted.toggle()
    print("ITEM \(items[id: id]!)")
  }
}

struct ContentView: View {
  
  @StateObject var viewModel = ViewModel(count: 1000)
  
  var body: some View {
    List(viewModel.items) { item in
      HStack {
        Text(item.name)
        Toggle(item.isCompleted ? "Completed" : "Incomplete", isOn: .init(
          get: { item.isCompleted },
          set: { _ in viewModel.toggleComplete(id: item.id)}
        )
        ).toggleStyle(.button)
      }
    }
    
  }
}

struct ContentView_Previews: PreviewProvider {
  static var previews: some View {
    ContentView()
  }
}