title: Vertically center NSTextAttachment in a UITextView
body: <p>I have an custom <code>NSTextAttachment</code> class which I use to scale images inside a <code>UITextView</code> (based on the <a href="https://stackoverflow.com/a/21150241">answer here</a>). This works great in <code>portrait</code> mode. In <code>landscape</code> mode, the images do not cover the whole screen and I want to center them in the <code>textview</code>.</p>
  
  <p>Making changes to the bounds in the custom class (in <code>attachmentBoundsForTextContainer:</code>) does not make a difference (tried changing both <code>x</code> and <code>y</code> in the bounds). How else can this be changed? Thanks.</p>