MainActivity

protected override void OnCreate(Bundle bundle)
{
  TabLayoutResource = Resource.Layout.Tabbar;
  ToolbarResource = Resource.Layout.Toolbar;

  base.OnCreate(bundle);

  global::Xamarin.Forms.Forms.Init(this, bundle);
  // add this line 
  DependencyService.Register<Interfaces.IRendererResolver, Services.RendererResolver>();

  LoadApplication(new App());
}