spine-runtimes/spine-flutter/example/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
    }
}