CachingStrategy OnPlatform axml

Hello, I would like to choose the Caching Strategy for each platform.
My code is as follows but does not work:

<ListView> <ListView.CachingStrategy> <OnPlatform x:TypeArguments="x:String" iOS="RetainElement" Android="RecycleElement" /> </ListView.CachingStrategy> <ListView.ItemTemplate> <DataTemplate> <ViewCell> ... </ViewCell> </DataTemplate> </ListView.ItemTemplate> </ListView>

How can I do it?

Thank you.