This components must be upgrade
https://components.xamarin.com/view/googleplusandplayios
Apple rejected my app with this motivation
"We noticed an issue in your app that contributes to a lower quality user experience than Apple users expect:
When the user attempts to login with Google +, a web page in mobile Safari opens and then returns the user to the app. The user should be able to log in without opening Safari first. It would be appropriate for this login to be placed within a webview.
Next Steps
It would be appropriate to revise your app to address all instances of this type of issue. "