From 084d60883bcdbda434ab9f3db8637de956eb97da Mon Sep 17 00:00:00 2001
From: Levi McCallum <levi.mccallum@nfl.com>
Date: Wed, 21 Oct 2015 23:04:21 -0700
Subject: [PATCH] Add assertion to flow layout inspector down casting

---
 AsyncDisplayKit/ASCollectionView.mm | 1 +
 1 file changed, 1 insertion(+)

diff --git a/AsyncDisplayKit/ASCollectionView.mm b/AsyncDisplayKit/ASCollectionView.mm
index 31191d42d3..08f4b43502 100644
--- a/AsyncDisplayKit/ASCollectionView.mm
+++ b/AsyncDisplayKit/ASCollectionView.mm
@@ -256,6 +256,7 @@ static BOOL _isInterceptedSelector(SEL sel)
 {
     if (_flowLayoutInspector == nil) {
         UICollectionViewFlowLayout *layout = (UICollectionViewFlowLayout *)self.collectionViewLayout;
+        ASDisplayNodeAssertNotNil(layout, @"Collection view layout must be a flow layout to use the built-in inspector");
         _flowLayoutInspector = [[ASCollectionViewFlowLayoutInspector alloc] initWithCollectionView:self
                                                                                         flowLayout:layout];
     }