Clean up supplementary nodes in data controller store on each reload

AsyncDisplayKit/Details/ASCollectionDataController.mm

@@ -47,7 +47,13 @@
 - (void)willReloadData
 {
   [_pendingNodes enumerateKeysAndObjectsUsingBlock:^(NSString *kind, NSMutableArray *nodes, BOOL *stop) {
-    LOG(@"Batch layout nodes of kind: %@, (%@)", kind, nodes);
+    // Remove everything that existed before the reload, now that we're ready to insert replacements
+    NSArray *indexPaths = [self indexPathsForEditingNodesOfKind:kind];
+    [self deleteNodesOfKind:kind atIndexPaths:indexPaths completion:nil];
+    
+    NSArray *editingNodes = [self editingNodesOfKind:kind];
+    NSMutableIndexSet *indexSet = [[NSMutableIndexSet alloc] initWithIndexesInRange:NSMakeRange(0, editingNodes.count)];
+    [self deleteSectionsOfKind:kind atIndexSet:indexSet completion:nil];
 
     // Insert each section
     NSUInteger sectionCount = [self.collectionDataSource dataController:self numberOfSectionsForSupplementaryKind:kind];
@@ -60,6 +66,8 @@
     [self batchLayoutNodes:nodes ofKind:kind atIndexPaths:_pendingIndexPaths[kind] completion:^(NSArray *nodes, NSArray *indexPaths) {
       [self insertNodes:nodes ofKind:kind atIndexPaths:indexPaths completion:nil];
     }];
+    _pendingNodes[kind] = [NSArray array];
+    _pendingIndexPaths[kind] = [NSArray array];
   }];
 }
 

AsyncDisplayKit/Details/ASDataController+Subclasses.h

@@ -32,9 +32,21 @@
 
 /**
  * Subclasses can override this to reload data after the abstract data controller deletes its old data and before it reloads the new.
+ *
+ * @discussion Invoked on the editing transaction queue.
  */
 - (void)willReloadData;
 
+/**
+ * Provides a collection of index paths for nodes of the given kind that are currently in the editing store
+ */
+- (NSArray *)indexPathsForEditingNodesOfKind:(NSString *)kind;
+
+/**
+ * Read-only access to the underlying editing nodes of the given kind
+ */
+- (NSArray *)editingNodesOfKind:(NSString *)kind;
+
 /**
  * Read only access to the underlying completed nodes of the given kind
  */

AsyncDisplayKit/Details/ASDataController.mm

@@ -786,6 +786,16 @@ static void *kASSizingQueueContext = &kASSizingQueueContext;
 
 #pragma mark - Data Querying (Subclass API)
 
+- (NSArray *)indexPathsForEditingNodesOfKind:(NSString *)kind
+{
+  return _editingNodes[kind] != nil ? ASIndexPathsForMultidimensionalArray(_editingNodes[kind]) : [NSArray array];
+}
+
+- (NSArray *)editingNodesOfKind:(NSString *)kind
+{
+  return _editingNodes[kind] != nil ? _editingNodes[kind] : [NSArray array];
+}
+
 - (NSArray *)completedNodesOfKind:(NSString *)kind
 {
   return _completedNodes[kind];