Check for nil elements on ASTableView as well #trivial (TextureGroup#710

)
AtomTickets · Apr 25, 2018 · 0908311 · 0908311
1 parent b017f4a
commit 0908311
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Showing 2 changed files with 27 additions and 4 deletions.
diff --git a/Source/ASCollectionView.mm b/Source/ASCollectionView.mm
@@ -1174,7 +1174,7 @@ - (void)collectionView:(UICollectionView *)collectionView willDisplayCell:(UICol
   ASCellNode *cellNode = element.node;
   cellNode.scrollView = collectionView;
 
-  // Update the selected background view in collectionView:willDisplayCell:forItemAtIndexPath: otherwise it could be to
+  // Update the selected background view in collectionView:willDisplayCell:forItemAtIndexPath: otherwise it could be too
   // early e.g. if the selectedBackgroundView was set in didLoad()
   cell.selectedBackgroundView = cellNode.selectedBackgroundView;
 

diff --git a/Source/ASTableView.mm b/Source/ASTableView.mm
@@ -130,6 +130,15 @@ - (void)setElement:(ASCollectionElement *)element
   [node __setHighlightedFromUIKit:self.highlighted];
 }
 
+- (BOOL)consumesCellNodeVisibilityEvents
+{
+  ASCellNode *node = self.node;
+  if (node == nil) {
+    return NO;
+  }
+  return ASSubclassOverridesSelector([ASCellNode class], [node class], @selector(cellNodeVisibilityEvent:inScrollView:withCellFrame:));
+}
+
 - (void)setSelected:(BOOL)selected animated:(BOOL)animated
 {
   [super setSelected:selected animated:animated];
@@ -971,7 +980,14 @@ - (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)sou
 - (void)tableView:(UITableView *)tableView willDisplayCell:(_ASTableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
 {
   ASCollectionElement *element = cell.element;
-  [_visibleElements addObject:element];
+  if (element) {
+    ASDisplayNodeAssertTrue([_dataController.visibleMap elementForItemAtIndexPath:indexPath] == element);
+    [_visibleElements addObject:element];
+  } else {
+    ASDisplayNodeAssert(NO, @"Unexpected nil element for willDisplayCell: %@, %@, %@", cell, self, indexPath);
+    return;
+  }
+
   ASCellNode *cellNode = element.node;
   cellNode.scrollView = tableView;
 
@@ -991,15 +1007,22 @@ - (void)tableView:(UITableView *)tableView willDisplayCell:(_ASTableViewCell *)c
 
   [_rangeController setNeedsUpdate];
 
-  if (ASSubclassOverridesSelector([ASCellNode class], [cellNode class], @selector(cellNodeVisibilityEvent:inScrollView:withCellFrame:))) {
+  if ([cell consumesCellNodeVisibilityEvents]) {
     [_cellsForVisibilityUpdates addObject:cell];
   }
 }
 
 - (void)tableView:(UITableView *)tableView didEndDisplayingCell:(_ASTableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
 {
+  // Retrieve the element from cell instead of visible map because at this point visible map could have been updated and no longer holds the element.
   ASCollectionElement *element = cell.element;
-  [_visibleElements removeObject:element];
+  if (element) {
+    [_visibleElements removeObject:element];
+  } else {
+    ASDisplayNodeAssert(NO, @"Unexpected nil element for didEndDisplayingCell: %@, %@, %@", cell, self, indexPath);
+    return;
+  }
+
   ASCellNode *cellNode = element.node;
 
   [_rangeController setNeedsUpdate];