How to style ListViewItem alternatively in Xamarin.Forms ListView

The SfListView allows applying alternate row styling for items by finding the index of the underlying object using IValueConverter.

<ContentPage xmlns:syncfusion="clr-namespace:Syncfusion.ListView.XForms;assembly=Syncfusion.SfListView.XForms">
    <ContentPage.Resources>
        <ResourceDictionary>
            <local:IndexToColorConverter x:Key="IndexToColorConverter"/>
        </ResourceDictionary>
    </ContentPage.Resources>
    <ContentPage.Content>
        <syncfusion:SfListView x:Name="listView" ItemsSource="{Binding Items}" ItemSize="50">
            <syncfusion:SfListView.ItemTemplate>
                <DataTemplate>
                    <Grid BackgroundColor="{Binding .,Converter={StaticResource IndexToColorConverter},ConverterParameter={x:Reference Name=listView}}">
                        <Label Text="{Binding ContactName}" />
                        <Label Text="{Binding ContactNumber}" />
                    </Grid>
                </DataTemplate>
            </syncfusion:SfListView.ItemTemplate>
        </syncfusion:SfListView>
    </ContentPage.Content>
</ContentPage>

public class IndexToColorConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        var listview = parameter as SfListView;
        var index = listview.DataSource.DisplayItems.IndexOf(value);

        if (index % 2 == 0)
            return Color.LightGray;
        return Color.Aquamarine;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
    }
}

To know more about ListViewItem appearance customization, you can refer our Ug documentation from here.