在AppDelegate.swift文件中，我具有以下代码：
import UIKit
@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
var mpcHandler:MPCHandler = MPCHandler()
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
return true
}
func applicationWillResignActive(_ application: UIApplication) {
}
func applicationDidEnterBackground(_ application: UIApplication) {
}
func applicationWillEnterForeground(_ application: UIApplication) {
}
func applicationDidBecomeActive(_ application: UIApplication) {
}
func applicationWillTerminate(_ application: UIApplication) {
}
}
对于语句：var mpcHandler：MPCHandler = MPHandler（）我遇到了错误。有什么建议吗？