How to pass selected row's data to a command?

<?xml version="1.0" encoding="utf-8" ?>

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"

             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"

             xmlns:syncfusion="clr-namespace:Syncfusion.SfDataGrid.XForms;assembly=Syncfusion.SfDataGrid.XForms"

             xmlns:local="clr-namespace:SelectionSample"

             x:Class="SelectionSample.MainPage">

  <ContentPage.BindingContext>

    <local:ViewModel x:Name="viewModel" />

  </ContentPage.BindingContext>

  <ContentPage.Resources>

    <ResourceDictionary>

      <local:CustomConverter x:Key="gridSelectionChangedEventArgs" />

    </ResourceDictionary>

  </ContentPage.Resources>

  <syncfusion:SfDataGrid x:Name="dataGrid"

                     ColumnSizer="Star"

                     SelectionMode="Single"

                     ItemsSource="{Binding OrderInfo}">

    <syncfusion:SfDataGrid.Behaviors>

      <local:CustomBehavior Command="{Binding SelectionCommand}"

                            Converter="{StaticResource gridSelectionChangedEventArgs}" />

    </syncfusion:SfDataGrid.Behaviors>

  </syncfusion:SfDataGrid>

</ContentPage>s