private string GetKey(object item)
{
// This function takes in the item at the top of the viewport at the moment of navigating away from the page, and returns
// a key corresponding to that item. the implementation of this function is dependent on the data model you are using. In this
// function we also save the fully rendered _persistedItemContainerHeight. You do not need to do this if all of your items have
// the same fixed height. Finally, we save the key into a variable so it can be used outside of ListViewPersistenceHelper functions
var singleItem = item as Item;
if (singleItem != null)
{
_persistedItemContainerHeight = (ItemsListView.ContainerFromItem(item) as ListViewItem).ActualHeight;
_persistedItemKey = singleItem.Id;
return(_persistedItemKey);
}
else
{
return(string.Empty);
}
}
