Merge branch 'charlesmchen/conversationScrollEdgeCase'

Signal/src/ViewControllers/ConversationView/ConversationViewController.m

@@ -504,6 +504,14 @@ typedef NS_ENUM(NSInteger, MessagesRangeSizeMode) {
     [self.collectionView autoPinWidthToSuperview];
     [self.collectionView autoPinToTopLayoutGuideOfViewController:self withInset:0];
 
+    // Fix a bug that only affects iOS 11.0.x and 11.1.x.
+    if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(11, 0) && !SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(11, 2)) {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wpartial-availability"
+        self.collectionView.contentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentNever;
+#pragma clang diagnostic pop
+    }
+
     _inputToolbar = [ConversationInputToolbar new];
     self.inputToolbar.inputToolbarDelegate = self;
     self.inputToolbar.inputTextViewDelegate = self;