title: Xamarin.Forms List view with caching strategy recycle element won't refresh visible elements
body: <p>I have a project in Xamarin.Forms which contains a listView bound to an ObservableCollection.</p>
  
  <p>The listView contains cells, each with a label and a switch. I have two buttons above that list : Select all &amp; Unselect all. Those buttons should toggle all the switches accordingly (and hopefully update the UI state of the switch) : Select all should refresh my listView with all switches toggled ON and Unselect all should refresh my listView with all switches toggled OFF.</p>
  
  <p>I also have a caching strategy on that list set to "Recycle element".</p>
  
  <p>The interesting part is : When I click on 'Select all' or 'Unselect all' button, the upper part of the listView (which is visible on screen) is not refresh <strong>BUT</strong> when I scroll down the listView, the new generated cells are updated since they are new due to the caching strategy. Also when I scroll back up, the old cells are also refreshed since they were recycled.</p>
  
  <p>How can I refresh the switch state in my listView <strong>without</strong> scrolling it ?</p>
  
  <p>Many thanks in advance.</p>