How to launch my application from gmail attachment + xamarin

I have attachment in my gmail, and that attachment is of my extension like .xxx now i want to launch my application using that attachment.

I am not sure how to get my intent into onCreate method of my application.

I am sure that onCreate is going to call and over there i need to check my intent and need to proceed further.

When i tried below code my application got crash.

if (Intent!= null && Intent.Action.Equals(Intent.ActionView)) {

// my function }

on above line of code my Intent is not null but my Intent.Action is null so that means that i am not getting intent which i want.

Thanks in advanced