AppDelegate-Google.swift

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        
        FIRApp.configure()
        GIDSignIn.sharedInstance().clientID = FIRApp.defaultApp()?.options.clientID
        GIDSignIn.sharedInstance().delegate = firebaseManager
       
        return true

    }

func application(_ app: UIApplication, open url: URL, options: [UIApplicationOpenURLOptionsKey : Any] = [:]) -> Bool {
        
        let sourceApplication = options[UIApplicationOpenURLOptionsKey.sourceApplication] as? String
        let annotation = options[UIApplicationOpenURLOptionsKey.annotation]
        let urlString = url.absoluteString
        if urlString.contains("com.googleusercontent") {
            return GIDSignIn.sharedInstance().handle(url, sourceApplication: sourceApplication, annotation: annotation)
        }
        
        return true
    }