Create a .NET MAUI application from scratch

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="MyDigiIoTMAUIApp.MainPage">
</ContentPage>

using DigiIoT.Maui.Devices.XBee;
using DigiIoT.Maui.Exceptions;
using DigiIoT.Maui.Models;
using XBeeLibrary.Core.Exceptions;

namespace MyDigiIoTMAUIApp;

public partial class MainPage : ContentPage
{
    // Constants.
    // TODO: replace with the Bluetooth MAC address of your XBee device.
    private static readonly string BLE_MAC_ADDR = "00:0B:57:C2:66:D5";
    // TODO: replace with the Bluetooth password of your XBee device.
    private static readonly string BLE_PASSWORD = "12345";

    // Variables.
    private readonly ActivityIndicator activityIndicator;
    private readonly Label statusLabel;
    private readonly XBeeBLEDevice myXBeeDevice = null;

    public MainPage()
    {
        InitializeComponent();

        // Declare the XBee BLE device to connect to.
        myXBeeDevice = new XBeeBLEDevice(BLE_MAC_ADDR, BLE_PASSWORD);
        // Configure the page title.
        Title = "XBee BLE Application";
        // Set the page content.
        StackLayout contentLayout = new()
        {
            VerticalOptions = LayoutOptions.Center,
            HorizontalOptions = LayoutOptions.Center
        };
        activityIndicator = new ActivityIndicator
        {
            Color = Colors.DarkGray
        };
        statusLabel = new Label
        {
            HorizontalOptions = LayoutOptions.Center,
            Margin = new Thickness(25, 0),
            TextColor = Colors.DarkGray,
            FontSize = 16
        };
        contentLayout.Children.Add(activityIndicator);
        contentLayout.Children.Add(statusLabel);
        Content = contentLayout;
    }

    protected override async void OnAppearing()
    {
        base.OnAppearing();

        // Show an indicator while connecting to the device.
        activityIndicator.IsRunning = true;
        statusLabel.TextColor = Colors.DarkGray;
        statusLabel.Text = string.Format("Connecting to device {0}...", BLE_MAC_ADDR);
        // The connection process blocks the UI interface, so it must be done in a different thread.
        await Task.Run(() =>
        {
            try
            {
                // Check BLE status.
                try
                {
                    DigiBLEManager.ValidateBluetoothStatus();
                } catch (DigiIoTException ex)
                {
                    MainThread.BeginInvokeOnMainThread(() =>
                    {
                        DisplayAlert("Error checking Bluetooth", ex.Message, "OK");
                    });
                }

                // Open the connection with the device.
                myXBeeDevice.Connect();
                MainThread.BeginInvokeOnMainThread(() =>
                {
                    activityIndicator.IsRunning = false;
                    statusLabel.TextColor = Colors.DarkGreen;
                    statusLabel.Text = "Connected successfully to " + BLE_MAC_ADDR;
                });
            }
            catch (BluetoothAuthenticationException e)
            {
                // Error authenticating the device, check password.
                MainThread.BeginInvokeOnMainThread(() =>
                {
                    activityIndicator.IsRunning = false;
                    statusLabel.TextColor = Colors.DarkRed;
                    statusLabel.Text = "Invalid password: " + e.Message;
                });
            }
            catch (DigiIoTException e)
            {
                // Error opening the connection with the device.
                MainThread.BeginInvokeOnMainThread(() =>
                {
                    activityIndicator.IsRunning = false;
                    statusLabel.TextColor = Colors.DarkRed;
                    statusLabel.Text = "Error connecting to device: " + e.Message;
                });
            }
        });
    }

    protected override void OnDisappearing()
    {
        base.OnDisappearing();

        // Disconnect the device.
        activityIndicator.IsRunning = false;
        statusLabel.TextColor = Colors.DarkGray;
        statusLabel.Text = "Disconnected from device.";
        if (myXBeeDevice.IsConnected)
            myXBeeDevice.Disconnect();
    }
}