How to get the activity indicator to run on the bottom of the collectionview to indicate that more items are being loaded?

I was wondering how I could add an activity indicator to the footer of the collection view in Xamarin Forms to show that more items are being fetched from the server.

XAML

<CollectionView Grid.Row="1" x:Name="Posts" SelectionMode="Single" SelectionChanged="Posts_SelectionChanged" RemainingItemsThreshold="5" RemainingItemsThresholdReached="Posts_RemainingItemsThresholdReached">
  <CollectionView.ItemTemplate>
        <DataTemplate>
            <StackLayout Padding="8, 8, 8, 0">
                // Some XAML
            </StackLayout>
        </DataTemplate>
    </CollectionView.ItemTemplate>
</CollectionView>