using Android.Support.Design.Widget;
using Android.Support.V7.Widget;
using Android.Support.V7.App;
using Android.Support.V4.Widget;
namespace KobitAndroidBeta

[Activity(Label = "DrawerMenu")]
public class DrawerMenu : Activity
{
    DrawerLayout drawerLayout;

    protected override void OnCreate(Bundle savedInstanceState)
    {


        base.OnCreate(savedInstanceState);

        SetContentView(Resource.Layout.Menu);
        drawerLayout = FindViewById<DrawerLayout>(Resource.Id.drawer_layout);

        // Init toolbar
        var toolbar = FindViewById<Toolbar>(Resource.Id.toolbar);
        SetSupportActionBar(toolbar); // AQUI ES EL ERROR, NO ENTIENDO PORQUE

        // Attach item selected handler to navigation view
        var navigationView = FindViewById<NavigationView>(Resource.Id.nav_view);
        navigationView.NavigationItemSelected += NavigationView_NavigationItemSelected; ;

        // Create ActionBarDrawerToggle button and add it to the toolbar
        var drawerToggle = new ActionBarDrawerToggle(this, drawerLayout, toolbar, Resource.String.open_drawer, Resource.String.close_drawer);
        drawerLayout.SetDrawerListener(drawerToggle);
        drawerToggle.SyncState();
    }

    private void NavigationView_NavigationItemSelected(object sender, NavigationView.NavigationItemSelectedEventArgs e)
    {
        switch (e.MenuItem.ItemId)
        {
            case (Resource.Id.nav_home):
                // React on 'Home' selection
                break;
            case (Resource.Id.nav_messages):
                // React on 'Messages' selection
                break;
            case (Resource.Id.nav_friends):
                // React on 'Friends' selection
                break;
            case (Resource.Id.nav_discussion):
                // React on 'Discussion' selection
                break;
        }

        // Close drawer
        drawerLayout.CloseDrawers();
    }
}

public class DrawerMenu : AppCompatActivity
{
  //...
}