title: reload collection view by press back bar button item
body: <p>I have a <code>collectionView</code> in my app that when the user taps one cell of it, the <code>collectionView</code> will reload data, in detail, I have an album that it could contain another album when user choose one of them it shows albums inside of that.<br></p>
  
  <p>Now I want when user click on <code>backBarButton</code> the past data appears on <code>collectionView</code> (super-albums), but now <code>backbarButton</code> shows the past VC.<br></p>
  
  <p>I use navigationController and show module segues between VCs.<br></p>
  
  <p><strong>Q:</strong> How should I implement that?</p>