MasterDetailPage: How I can show "Master" page from "Detail" page

Hello!

I use MasterDetailPage and PageRenderer. And I need a button for show menu (Master page).

I can show it thru PushModal:
menuBtn.TouchUpInside += async (s, ev) => await page.Navigation.PushModalAsync (new DrawerPage ());
but i think it not good idea.

iOS PageRenderer:

public class MapPageRenderer : PageRenderer
    {
        ...
        protected override void OnElementChanged (VisualElementChangedEventArgs e)
        {
            ...
            var page = e.NewElement as MapPage;
            ...
            var menuBtn = UIButton.FromType(UIButtonType.RoundedRect);
            menuBtn.TouchUpInside += (s, ev) => {
                ???
            };
        }

Anyone have ideas?
Thanx!