How to understand whether the user scrolled to the end of the list or to the beginning ListView in Xamarin.Forms?

I have a ListView control, it stores a list of messages (chat). How to understand if the user scrolled to the end of the list or if he is somewhere at the beginning.

My ListView xaml

<ListView
              
                ItemTapped="MyListView_ItemTapped"
                Grid.Row="0" Grid.Column="0"
                IsRefreshing="{Binding IsRefreshing}" 
                RefreshCommand="{Binding UpdateList}"
                ItemTemplate="{StaticResource chatDataTemplateSelector}"  
                ItemsSource="{Binding MessageList}"
                Background="#1D2733" 
                IsPullToRefreshEnabled="True" 
                RefreshControlColor="Cyan"  
                Margin="0,0,0,0" 
                SeparatorColor="Transparent"  
                x:Name="MyListView" 
                HasUnevenRows="true" 
                >
               
            </ListView>

Result Code: