From afbfcbdf04682dcecc7c16558d58e02039ad1e6a Mon Sep 17 00:00:00 2001
From: Ryan Wang <wanglun02@gmail.com>
Date: Mon, 12 Mar 2018 15:27:37 -0700
Subject: [PATCH] fixed Footer is sticky to the top

Summary:
if `stickyHeader` is true, the footer could be sticky to the top

Issue fixed: #1093

- [x] All tests pass. Demo project builds and runs.
- [x] I added tests, an experiment, or detailed why my change isn't tested.
- [x] I added an entry to the `CHANGELOG.md` for any breaking changes, enhancements, or bug fixes.
- [x] I have reviewed the [contributing guide](https://github.com/Instagram/IGListKit/blob/master/.github/CONTRIBUTING.md)
Closes https://github.com/Instagram/IGListKit/pull/1094

Differential Revision: D7246636

Pulled By: rnystrom

fbshipit-source-id: 9b7da52ab46229606b530a378c01d799767e27f2
---
 CHANGELOG.md                         |  2 ++
 Source/IGListCollectionViewLayout.mm | 39 ++++++++++++++--------------
 2 files changed, 22 insertions(+), 19 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 03c8efb0..47fcfed9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,8 @@ The changelog for `IGListKit`. Also see the [releases](https://github.com/instag
 ### Fixes
 - Copy objects when retrieving from datasource to prevent modification of models in binding section controller. [Kashish Goel](https://github.com/kashishgoel) [(#1109)](https://github.com/Instagram/IGListKit/pull/1109)
 
+- Fixed footer is sticky when `stickyHeader` is `true` [aelam](https://github.com/aelam) [(#1094)](https://github.com/Instagram/IGListKit/pull/1094)
+
 3.2.0
 -----
 
diff --git a/Source/IGListCollectionViewLayout.mm b/Source/IGListCollectionViewLayout.mm
index 06c5097a..8ee577a5 100644
--- a/Source/IGListCollectionViewLayout.mm
+++ b/Source/IGListCollectionViewLayout.mm
@@ -319,29 +319,30 @@ static void adjustZIndexForAttributes(UICollectionViewLayoutAttributes *attribut
 
     if ([elementKind isEqualToString:UICollectionElementKindSectionHeader]) {
         frame = entry.headerBounds;
+        
+
+        if (self.stickyHeaders) {
+            CGFloat offset = CGPointGetCoordinateInDirection(collectionView.contentOffset, self.scrollDirection) + self.topContentInset + self.stickyHeaderYOffset;
+
+            if (section + 1 == _sectionData.size()) {
+                offset = MAX(minOffset, offset);
+            } else {
+                const CGFloat maxOffset = CGRectGetMinInDirection(_sectionData[section + 1].bounds, self.scrollDirection) - CGRectGetLengthInDirection(frame, self.scrollDirection);
+                offset = MIN(MAX(minOffset, offset), maxOffset);
+            }
+            switch (self.scrollDirection) {
+                case UICollectionViewScrollDirectionVertical:
+                    frame.origin.y = offset;
+                    break;
+                case UICollectionViewScrollDirectionHorizontal:
+                    frame.origin.x = offset;
+                    break;
+            }
+        }
     } else if ([elementKind isEqualToString:UICollectionElementKindSectionFooter]) {
         frame = entry.footerBounds;
     }
 
-    if (self.stickyHeaders) {
-        CGFloat offset = CGPointGetCoordinateInDirection(collectionView.contentOffset, self.scrollDirection) + self.topContentInset + self.stickyHeaderYOffset;
-
-        if (section + 1 == _sectionData.size()) {
-            offset = MAX(minOffset, offset);
-        } else {
-            const CGFloat maxOffset = CGRectGetMinInDirection(_sectionData[section + 1].bounds, self.scrollDirection) - CGRectGetLengthInDirection(frame, self.scrollDirection);
-            offset = MIN(MAX(minOffset, offset), maxOffset);
-        }
-        switch (self.scrollDirection) {
-            case UICollectionViewScrollDirectionVertical:
-                frame.origin.y = offset;
-                break;
-            case UICollectionViewScrollDirectionHorizontal:
-                frame.origin.x = offset;
-                break;
-        }
-    }
-
     attributes = [UICollectionViewLayoutAttributes layoutAttributesForSupplementaryViewOfKind:elementKind withIndexPath:indexPath];
     attributes.frame = frame;
     adjustZIndexForAttributes(attributes);