title: Some files not showing in Xcode project navigator
body: <p>I added two files and a core data model to my Xcode project yesterday, and after saving I went off, but came back this morning to find they are not there. When I look in the project files, they <em>are</em> still there, but they, are not showing in the project navigator.</p>
  
  <p>When I build and run the app it doesn't crash (As in when I go on the views with one of those files, it recognises the file.)</p>
  
  <p>Is this a common problem and is there a way to fix this?</p>
  
  <p>Thanks in advance, any help is much appreciated</p>
  
  <p><strong>Edit:</strong> I do get this error though:</p>
  
  <pre><code>Failed to load model named [Project_name]
  CoreData: error:  Failed to load model named [Project_name]
  </code></pre>