void Save_Clicked(object sender, EventArgs args)
 {
     if (action == 0)
     {
         SetCategoriesViewModel.SaveNewPreference((SetCategoriesViewModel)this.BindingContext, Nav, this);
     }
     else if (action == 1)
     {
         SetCategoriesViewModel.SaveEditPreference((SetCategoriesViewModel)this.BindingContext, Nav);
     }
 }
 void Button_Clicked(object sender, EventArgs args)
 {
     SetCategoriesViewModel.ClearContents((SetCategoriesViewModel)this.BindingContext);
 }