How can I use Google's people API in Xamarin.iOS ?

Hi,
I have to access Google contact in our Xamarin.ios app so, We have generate Google's people API key and client id in https://console.developers.google.com/
But I don’t know how to consume API in Xamarin.ios app. We need to get Google contact details using Api.
We got some code for .net in Google documentation but unfortunately it’s not working in Xamarin.ios platform.
Please help me to solve this issue.