samples/cupertino_gallery/macos/Runner/AppDelegate.swift

import Cocoa
import FlutterMacOS

@main
class AppDelegate: FlutterAppDelegate {
  override func applicationShouldTerminateAfterLastWindowClosed(_ sender: NSApplication) -> Bool {
    return true
  }

  override func applicationSupportsSecureRestorableState(_ app: NSApplication) -> Bool {
    return true
  }
}