title: Make two UICollectionView's scroll synchronously with paging enabled
body: <p>Is it possible to make two collectionviews scroll synchronously, and if yes, how?</p>
  
  <p>I have this class, containing two collectionviews - one with a date, and another, containing a tableview, with elements matching the date from the first collectionview.
  When i scroll either the date, or the elements, i want them to follow each other.</p>
  
  <p>Here's some code, and what i've tried so far, but without any luck:</p>
  
  <p>I added the ScrollViewDelegate to my class, and tried this delegate-method:</p>
  
  <pre><code>func scrollViewDidScroll(scrollView: UIScrollView) {
      if scrollView.isEqual(dayCollectionView) {
          var offset = contentCollectionView.contentOffset
          offset.x = dayCollectionView.contentOffset.x
          contentCollectionView.setContentOffset(offset, animated: true)
      } else {
          var offset = dayCollectionView.contentOffset
          offset.x = contentCollectionView.contentOffset.x
          dayCollectionView.setContentOffset(offset, animated: true)
      }
  }
  </code></pre>
  
  <p>This method works some how, but the scrollview's are just going mental, and cant seem to stop scrolling, when they're first starts rolling.. </p>
  
  <p>I also tried this:</p>
  
  <pre><code>func scrollViewDidEndDecelerating(scrollView: UIScrollView) {
  
      if scrollView.isEqual(dayCollectionView) {
          // Days
          for cell in self.dayCollectionView.visibleCells() {
              if let indexPath = dayCollectionView.indexPathForCell(cell) {
                  contentCollectionView.scrollToItemAtIndexPath(indexPath, atScrollPosition: .None, animated: true)
              }
          }
      } else {
          // Classes
          for cell in self.contentCollectionView.visibleCells() {
              if let indexPath = contentCollectionView.indexPathForCell(cell) {
                  dayCollectionView.scrollToItemAtIndexPath(indexPath, atScrollPosition: .None, animated: true)
              }
          }
      }
  }
  </code></pre>
  
  <p>which is the best solution so far - but it's still not exactly what I want - this one scrolls, when the other collectionview is done scrolling.. But I want them to scroll synchronously :-)</p>
  
  <p>Any suggestions?</p>