Usage.cs

Task<int> ShowModalAletViewAsync (string title, string message, params string[] buttons)
{
    var alertView = new UIAlertView (title, message,  null, null, buttons);
    alertView.Show ();
    var tsc = new TaskCompletionSource<int> ();
    
    alertView.Clicked += (sender, buttonArgs) => {
    	Console.WriteLine ("User clicked on {0}", buttonArgs.ButtonIndex);		
    	tsc.TrySetResult(buttonArgs.ButtonIndex);
    };    
    return tsc.Task;
}		

//Usage
async Task PromptUser() {
    var result = await ShowModalAletViewAsync ("Alert", "Do you want to continue?", "Yes", "No");
    //process the result
}