Xamarin Form Apply Margin Per PlatForm

<Grid>
  <Grid.Margin>
       <OnPlatform x:TypeArguments="Thickness">
       <On Platform="iOS" Value="0,0,0,20" />
       <On Platform="Android, WinPhone, Windows" Value="0,0,0,30" />
      </OnPlatform>
  </Grid.Margin>
  <Grid.RowDefinitions>
    <RowDefinition Height="2*" />
    <RowDefinition Height="*" />
    <RowDefinition Height="200" />
  </Grid.RowDefinitions>
  <Grid.ColumnDefinitions>
    <ColumnDefinition Width="Auto" />
    <ColumnDefinition Width="*" />
  </Grid.ColumnDefinitions>
</Grid>