title: IServiceCollection not found in web API with MVC 6
body: <p>I am working with web API with MVC 6, here I am going in order to inject the repository into the controller, we need to register it with the DI container. Open the Startup.cs file.</p>
  
  <p>In the <code>ConfigureServices</code> method, going to add the highlighted code:</p>
  
  <pre><code>using System;
  using System.Collections.Generic;
  using System.Linq;
  using Microsoft.Owin;
  using Owin;
  using TodoApi.Models;
  
  [assembly: OwinStartup(typeof(TodoApi.Startup))]
  
  namespace TodoApi
  {
      public partial class Startup
      {
          public void Configuration(IAppBuilder app)
          {
              ConfigureAuth(app);
          }
  
          public void ConfigureServices(IServiceCollection services)
          {
              services.AddMvc();
              // Add our repository type
              services.AddSingleton&lt;ITodoRepository, TodoRepository&gt;();
          }
      }
  }
  </code></pre>
  
  <p>Its showing the error...</p>
  
  <blockquote>
    <p>The type or namespace name 'IServiceCollection' could not be found (are you missing a using directive or an assembly reference?)</p>
  </blockquote>