title: Xcode 4, subproject import problem
body: <p>I want to add a project as a subproject. When I drag the subproject into the main project it appears as a file reference rather than subproject. The picture below explains the problem:</p>
  
  <p><img src="https://i.stack.imgur.com/9h2fD.png" alt="Xcode subproject import problem"></p>