From 370364c9369b369927a748ac64d8fc613f0df9ca Mon Sep 17 00:00:00 2001
From: Michael Kirk <michael.code@endoftheworl.de>
Date: Tue, 21 Nov 2017 11:42:11 -0500
Subject: [PATCH] Scroll down button scrolls to unread

// FREEBIE
---
 .../ConversationViewController.m              | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/Signal/src/ViewControllers/ConversationView/ConversationViewController.m b/Signal/src/ViewControllers/ConversationView/ConversationViewController.m
index 909c8286b..d3c9f231e 100644
--- a/Signal/src/ViewControllers/ConversationView/ConversationViewController.m
+++ b/Signal/src/ViewControllers/ConversationView/ConversationViewController.m
@@ -2271,6 +2271,28 @@ typedef NS_ENUM(NSInteger, MessagesRangeSizeMode) {
 
 - (void)scrollDownButtonTapped
 {
+    NSIndexPath *indexPathOfUnreadMessagesIndicator = [self indexPathOfUnreadMessagesIndicator];
+    if (indexPathOfUnreadMessagesIndicator != nil) {
+        NSInteger unreadRow = indexPathOfUnreadMessagesIndicator.row;
+
+        BOOL isScrolledAboveUnreadIndicator = YES;
+        NSArray<NSIndexPath *> *visibleIndices = self.collectionView.indexPathsForVisibleItems;
+        for (NSIndexPath *indexPath in visibleIndices) {
+            if (indexPath.row > unreadRow) {
+                isScrolledAboveUnreadIndicator = NO;
+                break;
+            }
+        }
+
+        if (isScrolledAboveUnreadIndicator) {
+            // Only scroll as far as the unread indicator if we're scrolled above the unread indicator.
+            [[self collectionView] scrollToItemAtIndexPath:indexPathOfUnreadMessagesIndicator
+                                          atScrollPosition:UICollectionViewScrollPositionTop
+                                                  animated:YES];
+            return;
+        }
+    }
+
     [self scrollToBottomAnimated:YES];
 }