title: Unable to get a single large size for Facebook Graph API user's photos edge
body: <p>I am using the facebook sdk for login and user_photos purpose in a iOS Application.   </p>
  
  <p>The login is done and in the permissions I added the <code>user_photos</code> <code>readPermissions</code>.  </p>
  
  <p>But when I am trying to fetch the user photos using the graphPath: me/photos with <code>fields</code> parameters- <code>id,picture</code>, only the smallest of the images size is returned. I have tried using <code>picture.type(large)</code> or <code>picture.width(640)</code> , but nothing works.  </p>
  
  <p>I tried using the <code>images</code> parameter for <code>fields</code>, it returns all the sizes for the Photo node. </p>
  
  <p>I even tried using the edge <code>&lt;OBJECT_ID&gt;/picture</code> with <code>fields</code> parameter <code>picture</code>, but it gives a <code>facebook sdk error(error code 6)</code>.</p>
  
  <p>How to get the user photos with just a single photo link to a large size ?</p>
  
  <p>I am using the latest version of the SDK.</p>