How to Filter the items in AutoComplete Control?

//Code Explains how to filter the items in Autocomplete control
<Window x:Class="AutoComplete.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:AutoComplete"
xmlns:syncfusion="http://schemas.syncfusion.com/wpf"
Title="MainWindow" Height="350" Width="525">
<Grid>
<syncfusion:AutoComplete x:Name="Autocomplete" SelectedIndex="0" IsFilter="False" Source="Custom" HorizontalAlignment="Center" Height="40" DisplayMemberPath="item" CustomSource="{Binding item}" VerticalAlignment="Top" Width="150" Margin="176,125,177,0" >
</syncfusion:AutoComplete>
</Grid>
</Window>

//Code explains how to filter the items in AutoComplte control
namespace AutoComplete
{
public partial class MainWindow : Window
{
AutoCompleteList obj = new AutoCompleteList();
 public MainWindow()
{
InitializeComponent();
Autocomplete.CustomSource = obj;
}
}
public class AutomComp
{
 
public string item { get; set; 
}
public class AutoCompleteList : List<AutomComp>
{
public AutoCompleteList()
{
this.Add(new AutomComp() { item = "item 1" });
this.Add(new AutomComp() { item = "item 2" });
this.Add(new AutomComp() { item = "item 3" });
this.Add(new AutomComp() { item = "eitem 4" });
this.Add(new AutomComp() { item = "sitem 5" });
this.Add(new AutomComp() { item = "item 6" });
}
}
}