MainActivity.cs

    public class MainActivity : AppCompatActivity
    {
        DrawerLayout m_drawerLayout;
        NavigationView m_navigationView;

        protected override void OnCreate(Bundle bundle)
        {
            //...
            m_drawerLayout = FindViewById<DrawerLayout>(Resource.Id.maintActivity_drawerlayout);
            m_navigationView = FindViewById<NavigationView>(Resource.Id.maintActivity_navigationView);

            //Handle NavigationView's item click
            m_navigationView.NavigationItemSelected += M_navigationView_NavigationItemSelected;
        }

        public override bool OnOptionsItemSelected(IMenuItem item)
        {
            switch (item.ItemId)
            {
                //...

                //Handle sandwich menu icon click
                case Android.Resource.Id.Home:
                    //If menu is open, close it. Else, open it.
                    if (m_drawerLayout.IsDrawerOpen(GravityCompat.Start))
                        m_drawerLayout.CloseDrawers();
                    else
                        m_drawerLayout.OpenDrawer(GravityCompat.Start);
                    break;
            }

            return base.OnOptionsItemSelected(item);
        }
        
        private void M_navigationView_NavigationItemSelected(object sender, NavigationView.NavigationItemSelectedEventArgs e)
        {
            switch (e.MenuItem.ItemId)
            {
                case Resource.Id.leftmenu_profile:
                    break;

                case Resource.Id.leftmenu_shopping_list:
                    break;

                case Resource.Id.leftmenu_favorites:
                    break;

                case Resource.Id.leftmenu_params_option:
                    break;

                case Resource.Id.leftmenu_params_about:
                    break;
            }
            m_drawerLayout.CloseDrawer(GravityCompat.Start);
        }
    }