Reviewboard RBTools：从不同的diff获取已更改的文件

Question

假设我有一个包含10个文件的评论请求 从差异1和2，我只改变了1个文件

func targetContentOffsetForProposedContentOffset(proposedContentOffset:CGPoint, velocity: CGPoint) -> CGPoint
{

   let collectionViewSize:CGSize  = self.collectionView.bounds.size
   let proposedContentOffsetCenterX:CGFloat = proposedContentOffset.x + self.collectionView.bounds.size.width * 0.5

   let proposedRect:CGRect = self.collectionView.bounds
   //let candidateAttributes:UICollectionViewLayoutAttributes

   var candidateAttributes:[UICollectionViewLayoutAttributes]

   /* get stuck here in for loop*/
   for (attributes: [UICollectionViewLayoutAttributes] in layoutAttributesForElementsInRect:proposedRect)
   {

   }

上面的代码显示了相同数量的文件client = RBClient() root = client.get_root() files = root.get_files(review_request_id=1, diff_revision=1) files2 = root.get_files(review_request_id=1, diff_revision=2)

如何才能获取在diff 2中修改过的文件？