UserLoginModel.cs

using Facebook;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Navigation;

namespace MyoTestv4.Home
{
    public class UserLoginModel : INotifyPropertyChanged
    {
        private FacebookClient _fbClient;
        private FacebookClient _fbC;
        private string _accessToken;
        private string _userName;
        private string _gender;
        private string _link;

        public FacebookClient FbClient
        {
            get { return _fbClient; }
            set
            {
                if (Equals(value, _fbClient)) return;
                _fbClient = value;
                OnPropertyChanged();
            }
        }

        public FacebookClient FbC
        {
            get { return _fbC; }
            set
            {
                if (Equals(value, _fbC)) return;
                _fbC = value;
                OnPropertyChanged();
            }
        }

        public string AccessToken
        {
            get { return _accessToken; }
            set
            {
                if (value == _accessToken) return;
                _accessToken = value;
                OnPropertyChanged();
            }
        }

        public string UserName
        {
            get { return _userName; }
            set
            {
                if (value == _userName) return;
                _userName = value;
                OnPropertyChanged();
            }
        }

        public string Gender
        {
            get { return _gender; }
            set
            {
                if (value == _gender) return;
                _gender = value;
                OnPropertyChanged();
            }
        }

        public string Link
        {
            get { return _link; }
            set
            {
                if (value == _link) return;
                _link = value;
                OnPropertyChanged();
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;

        //[NotifyPropertyChangedInvocator]
        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            var handler = PropertyChanged;

            if (handler != null)
                handler.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}