         MCAAuthorizationManager.sharedInstance.registerAuthenticationDelegate(self, realm: GoogleAuthenticationManager.GOOGLE_REALM)
     }
     
-    public func onAuthenticationChallengeReceived(_ authContext : AuthenticationContext, challenge : AnyObject) {
+    public func onAuthenticationChallengeReceived(authContext : AuthenticationContext, challenge : AnyObject) {
         self.authContext = authContext
         
         guard let appID = challenge[GoogleAuthenticationManager.GOOGLE_APP_ID_KEY] as? String where appID == GIDSignIn.sharedInstance().clientID

    
    
    @objc
    public func sign(_ signIn: GIDSignIn!, didSignInFor user: GIDGoogleUser!, withError error: NSError!) {
        if (error == nil) {
            let idToken = user.authentication.idToken // Safe to send to the server
            if let unwrappedAuthContext = authContext {

    // pressed the Sign In button
    
    @objc
    public func signInWillDispatch(signIn: GIDSignIn!, error: NSError!) {
        // no needed work for now
    }
    
    // Present a view that prompts the user to sign in with Google
    @objc
    public func signIn(signIn: GIDSignIn!, presentViewController viewController: UIViewController!) {
        if var topController = UIApplication.sharedApplication().keyWindow?.rootViewController where self.localVC == nil {
            while let presentedViewController = topController.presentedViewController {
                topController = presentedViewController
            }
