在Xcode11.5中从AppDelegate访问ViewController (firebase谷歌登录)

import Firebase
import GoogleSignIn

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    FirebaseApp.configure()
    GIDSignIn.sharedInstance().clientID = FirebaseApp.app()?.options.clientID
    return true
}

func application(_ app: UIApplication, open url: URL, options: [UIApplication.OpenURLOptionsKey : Any] = [:]) -> Bool {
    return GIDSignIn.sharedInstance().handle(url)
}

import GoogleSignIn

class ViewController: UIViewController, GIDSignInDelegate {
    override func viewDidLoad() {
        super.viewDidLoad()
        
        GIDSignIn.sharedInstance()?.presentingViewController = self
        GIDSignIn.sharedInstance()?.delegate = self
    }
    
    @IBAction func googleSignInButtonTapped(_ sender: UIButton) {
        GIDSignIn.sharedInstance()?.signIn()
    }
    
    // 实现谷歌登录回调方法
    func sign(_ signIn: GIDSignIn!, didSignInFor user: GIDGoogleUser!, withError error: Error?) {
        if let error = error {
            print("谷歌登录出错：\(error.localizedDescription)")
            return
        }
        
        // 用户成功登录，可以在这里处理用户信息
        let userId = user.userID
        let fullName = user.profile.name
        let email = user.profile.email
        
        // 进行其他操作，例如跳转到下一个界面
    }
}