SearchBar в С#(mvvm)

Хочу сделать searchbar для поиска людей по имени или фамилии, но всё никак не получается. Вот код... PersonListViewModel.cs:

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Text; 
using System.Windows.Input;
using Xamarin.Forms;
using GenTree.Views;
using System.Linq;
using GenTree.Models;
namespace GenTree.ViewModels
{
 public class PersonsListViewModel : INotifyPropertyChanged
{
    public ObservableCollection<MainViewModel> Persons { get; set; }
    public event PropertyChangedEventHandler PropertyChanged;
    public ICommand CreatePersonCommand { protected set; get; }
    public ICommand DeletePersonCommand { protected set; get; }
    public ICommand SavePersonCommand { protected set; get; }
    public ICommand BackCommand { protected set; get; }
    public ICommand SelectPersonsCommand { protected set; get; }
    MainViewModel selectedPerson;
    public INavigation Navigation { get; set; }
    public PersonsListViewModel()
    {
        Persons = new ObservableCollection<MainViewModel>();
        CreatePersonCommand = new Command(CreatePerson);
        DeletePersonCommand = new Command(DeletePerson);
        SavePersonCommand = new Command(SavePerson);
        BackCommand = new Command(Back);
        //SelectPersonsCommand = new Command(SelectPersons);     попытка сделать поиск
    }
    public MainViewModel SelectedFriend
    {
        get { return selectedPerson; }
        set
        {
            if (selectedPerson != value)
            {
                MainViewModel tempPerson = value;
                selectedPerson = null;
                OnPropertyChanged("SelectedPerson");
                Navigation.PushAsync(new PersonPage(tempPerson));
            }
        }
    }
    protected void OnPropertyChanged(string propName)
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(propName));
    }
    private void CreatePerson()
    {
        Navigation.PushAsync(new PersonPage(new MainViewModel() { ListViewModel = this }));
    }
    private void Back()
    {
        Navigation.PopAsync();
    }
    private void SavePerson(object personObject)
    {
        MainViewModel person = personObject as MainViewModel;
        if (person != null && person.IsValid)
        {
            Persons.Add(person);
        }
        Back();
    }
    private void DeletePerson(object personObject)
    {
        MainViewModel person = personObject as MainViewModel;
        if (person != null)
        {
           Persons.Remove(person);
        }
        Back();
    }
    //private void SearchCommandExecute()
    //{
    //    var tempRecords = Persons.Where(p => p.Name.Contains(Text));
    //    Persons = new ObservableCollection<Person>(tempRecords);
    //}
}
}

Relatives.xaml:

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage Title="Relatives" Icon="family.png" BackgroundColor="LemonChiffon" xamarinforms:BottomBarPageExtensions.TabColor="#20b2aa"
xmlns="http://xamarin.com/schemas/2014/forms"
         xmlns:xamarinforms="clr-namespace:BottomBar.XamarinForms;assembly=BottomBar.XamarinForms"
         xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
         xmlns:local="clr-namespace:GenTree.ViewModels"
         x:Class="GenTree.Views.Relatives">
<!--<ContentPage.BindingContext>
        <local:MainViewModel/>
    </ContentPage.BindingContext>-->
<StackLayout>
    <SearchBar x:Name="MainSearchBar"
               SearchButtonPressed="MainSearchBar_SearchButtonPressed"/>
    <Button Text="Add" Command="{Binding CreatePersonCommand}" />
    <ListView x:Name="booksList" ItemsSource="{Binding Persons}"
          SelectedItem="{Binding SelectedPerson, Mode=TwoWay}" HasUnevenRows="True">
        <ListView.ItemTemplate>
            <DataTemplate>
                <ViewCell>
                    <ViewCell.View>
                        <StackLayout>
                            <Label Text="{Binding Name}" FontSize="Medium" />
                            <Label Text="{Binding Surname}" FontSize="Small" />
                        </StackLayout>
                    </ViewCell.View>
                </ViewCell>
            </DataTemplate>
        </ListView.ItemTemplate>
    </ListView>
</StackLayout>

Relatives.xaml.cs:

using System;
using System.Collections.Generic;
using System.Linq;
using GenTree.ViewModels;
using System.Text;
using System.Threading.Tasks;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;
namespace GenTree.Views
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class Relatives : ContentPage
{
    public Relatives ()
    {
        InitializeComponent ();
        BindingContext = new PersonsListViewModel(){ Navigation = this.Navigation};
    }
    private void MainSearchBar_SearchButtonPressed(object sender, EventArgs e)
    {
    }
}
}