c# - How do I use the event VisibilityChanged? -

i need re-run code contained within dela method onnavigatedto () when app resumes background. need event visibilitychanged: link msdn

protected async override void onnavigatedto(navigationeventargs e)         {                    //my code         } 

with event, each time app opened again background, code contained within dell'onnavigatedto runs again. how can use event? can not.

visibility changed relevant if page isn't in background. every time app opens goes onnavigatedto(), can make bool or counter check if first time entered page , decide based on inside onnavigatedto. example:

private override void onnavigatedto(navigationeventargs e) {      if(hasbeenhere) repeat_visit(args);      else first_visit(args); }