title: Why UICollectionView offset changes when keyboard appears
body: <p>I'm developing an iPad app, that has a horizontal <code>UICollectionView</code>. Each of the cells has a <code>UITextField</code>. When the <code>UITextField</code> becomes first responder, the keyboard automatically comes up, and surprisingly all the cells move upwards. </p>
  
  <p>I haven't implemented any logic for the cells to move upwards. Do you know why?</p>
  
  <p>I haven't found any documentation regarding this, and I'm unable to fix this.</p>