MasterPageViewModel.cs

using MasterDemo.Views;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Runtime.CompilerServices;

namespace MasterDemo
{
    /// <summary>
    /// Represents the <see cref="MasterPageViewModel"/>.
    /// </summary>
    public class MasterPageViewModel : INotifyPropertyChanged
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="MasterPageViewModel"/>.
        /// </summary>
        public MasterPageViewModel()
        {
            // defining the menu items.
            MenuItems = new ObservableCollection<MenuItem>(new[]
            {                    
                    new MenuItem { Title = "Home", TargetType = typeof(HomePage) },
                    new MenuItem { Title = "Profile", TargetType = typeof(ProfilePage) },
                    new MenuItem { Title = "Logout", TargetType = typeof(LogoutPage) },
                    new MenuItem { Title = "TabbedPage", TargetType = typeof(MainTabbedPage)}
            });
        }

        /// <summary>
        /// Gets or sets the menu items.
        /// </summary>
        /// <value>
        /// An ObservableCollection of <see cref="MenuItem"/>.
        /// </value>
        public ObservableCollection<MenuItem> MenuItems { get; set; }

        /// <summary>
        /// The event for changed properties.
        /// </summary>
        public event PropertyChangedEventHandler PropertyChanged;

        /// <summary>
        /// Callback method for <see cref="PropertyChanged"/>.
        /// </summary>
        /// <param name="propertyName">The propertyname. Default is an empty string.</param>
        void OnPropertyChanged([CallerMemberName] string propertyName = "")
        {
            if (PropertyChanged == null)
                return;

            PropertyChanged.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}