Improve README

README.md

@@ -44,22 +44,25 @@ Pinch-to-zoom works seamlessly in images.
 From your UICollectionView:
 
 ```swift
-override func collectionView(collectionView: UICollectionView, didSelectItemAtIndexPath indexPath: IndexPath) {
+override public func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
     guard let collectionView = self.collectionView else { return }
 
     let viewerController = ViewerController(initialIndexPath: indexPath, collectionView: collectionView)
+    viewerController.dataSource = self
+
     let headerView = HeaderView()
     headerView.viewDelegate = self
     self.viewerController?.headerView = headerView
+
     let footerView = FooterView()
     footerView.viewDelegate = self
     self.viewerController?.footerView = footerView
-    viewerController.dataSource = self
+
     self.presentViewController(viewerController, animated: false, completion: nil)
 }
 
 extension CollectionController: ViewerControllerDataSource {
-    func viewerController(viewerController: ViewerController, itemAtIndexPath indexPath: IndexPath) -> Viewable {
+    func viewerController(_ viewerController: ViewerController, viewableAt indexPath: IndexPath) -> Viewable {
         return self.photos[indexPath.row]
     }
 }