Phonebook/MainPage.xaml.cs

using Phonebook.Services;
using Contact = Phonebook.Models.Contact;
using Communication = Microsoft.Maui.ApplicationModel.Communication;
using Android.Content;

namespace Phonebook;

public partial class MainPage : ContentPage
{
    private ContactService _contactService;
    private DatabaseService _databaseService;
    
    public MainPage()
    {
        InitializeComponent();
        _contactService = IPlatformApplication.Current!.Services.GetService<ContactService>()!;
        _databaseService = IPlatformApplication.Current!.Services.GetService<DatabaseService>()!;
    }

    private async void OnContactsUpdated()
    {
        await UpdateList();
    }

    protected override async void OnAppearing()
    {
        base.OnAppearing();
        await UpdateList();
        _contactService.OnContactsUpdated += OnContactsUpdated;
    }

    protected override void OnDisappearing()
    {
        base.OnDisappearing();
        _contactService.OnContactsUpdated -= OnContactsUpdated;
    }

    private async void OnContactSelected(object sender, SelectionChangedEventArgs e)
    {
        if (e.CurrentSelection.FirstOrDefault() is not Contact selectedContact) 
            return;
        
        await Navigation.PushAsync(new ContactDetailPage(selectedContact));
        contactsList.SelectedItem = null;
    }

    private async void OnSearchTextChanged(object sender, TextChangedEventArgs e)
    {
        await UpdateList();
    }

    private async Task UpdateList()
    {
        contactsList.ItemsSource = await _databaseService.SearchContactsAsync(searchBar.Text);
    }

    private async void OnAddContactClicked(object sender, EventArgs e)
    {
        await Navigation.PushAsync(new ContactDetailPage(new Contact()));
    }
}