public viewAnnouncement()
 {
     tiltes = new List <string>();
     posts  = new mainDal();
     InitializeComponent();
     li = posts.getALLPost();
     foreach (announcement a in li)
     {
         string til = a.Title;
         tiltes.Add(til);
     }
     this.titleOfAnouncement.ItemsSource = tiltes;
 }