WPF UnityContainer traditional using Microsoft.Practices.Unity;

1.Install-Package Unity -Version 4.0.1

2.

using Microsoft.Practices.Unity;
using WpfApp9.IModels;
using WpfApp9.Models;
using WpfApp9.ViewModel;

namespace WpfApp9
{
    /// <summary>
    /// Interaction logic for App.xaml
    /// </summary>
    public partial class App : Application
    {
        protected override void OnStartup(StartupEventArgs e)
        {
            base.OnStartup(e);
            IUnityContainer unityContainer = new UnityContainer();
            unityContainer.RegisterType<IDateModel, DateModel>();
            var mainVM = unityContainer.Resolve<MainVM>();
            var window = new MainWindow
            {
                DataContext = mainVM
            };
            window.Show();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace WpfApp9.IModels
{
    interface IDateModel
    {
        string GetDateTime();
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using WpfApp9.IModels;
namespace WpfApp9.Models
{
    public class DateModel : IDateModel
    {
        public string DateTimeNow { get; set; }

        public DateModel()
        {
            DateTimeNow = GetDateTime();
        }

        public string GetDateTime()
        {
            return DateTime.Now.ToString("yyyyMMddHHmmssffff");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using WpfApp9.Models;

namespace WpfApp9.ViewModel
{
    public class MainVM
    {
        private DateModel dateModel;
        public MainVM()
        {
        }

        public MainVM(DateModel dateHelper)
        {
            dateModel = dateHelper;
        }
    }
}