Consider supplementary views when sending display events

CHANGELOG.md

@@ -28,6 +28,10 @@ This release closes the [3.0.0 milestone](https://github.com/Instagram/IGListKit
 
 - Empty Views now move with Refresh Controls, and no longer use the `_collectionView.backgroundView` property. [dshahidehpour](https://github.com/dshahidehpour) [(#462)](https://github.com/Instagram/IGListKit/pull/462)]
 
+### Fixes
+
+- Consider supplementary views with display and end-display events. [Ryan Nystrom](https://github.com/rnystrom) [(#470)](https://github.com/Instagram/IGListKit/pull/470)
+
 
 ### Enhancements
 

Source/IGListAdapter.m

@@ -17,7 +17,7 @@
 #import "IGListSectionControllerInternal.h"
 
 @implementation IGListAdapter {
-    NSMapTable<UICollectionViewCell *, IGListSectionController<IGListSectionType> *> *_cellSectionControllerMap;
+    NSMapTable<UICollectionReusableView *, IGListSectionController<IGListSectionType> *> *_viewSectionControllerMap;
     BOOL _isDequeuingCell;
     BOOL _isSendingWorkingRangeDisplayUpdates;
 }
@@ -49,7 +49,7 @@ - (instancetype)initWithUpdater:(id <IGListUpdatingDelegate>)updater
         _displayHandler = [[IGListDisplayHandler alloc] init];
         _workingRangeHandler = [[IGListWorkingRangeHandler alloc] initWithWorkingRangeSize:workingRangeSize];
 
-        _cellSectionControllerMap = [NSMapTable mapTableWithKeyOptions:NSMapTableObjectPointerPersonality | NSMapTableStrongMemory
+        _viewSectionControllerMap = [NSMapTable mapTableWithKeyOptions:NSMapTableObjectPointerPersonality | NSMapTableStrongMemory
                                                           valueOptions:NSMapTableStrongMemory];
 
         _updater = updater;
@@ -396,7 +396,7 @@ - (NSArray *)objects {
     NSArray<UICollectionViewCell *> *visibleCells = [self.collectionView visibleCells];
     NSMutableSet *visibleSectionControllers = [NSMutableSet new];
     for (UICollectionViewCell *cell in visibleCells) {
-        IGListSectionController *sectionController = [self sectionControllerForCell:cell];
+        IGListSectionController *sectionController = [self sectionControllerForView:cell];
         IGAssert(sectionController != nil, @"Section controller nil for cell %@", cell);
         if (sectionController) {
             [visibleSectionControllers addObject:sectionController];
@@ -410,7 +410,7 @@ - (NSArray *)visibleObjects {
     NSArray<UICollectionViewCell *> *visibleCells = [self.collectionView visibleCells];
     NSMutableSet *visibleObjects = [NSMutableSet new];
     for (UICollectionViewCell *cell in visibleCells) {
-        IGListSectionController<IGListSectionType> *sectionController = [self sectionControllerForCell:cell];
+        IGListSectionController<IGListSectionType> *sectionController = [self sectionControllerForView:cell];
         IGAssert(sectionController != nil, @"Section controller nil for cell %@", cell);
         if (sectionController != nil) {
             const NSInteger section = [self sectionForSectionController:sectionController];
@@ -626,21 +626,21 @@ - (NSIndexPath *)indexPathForSectionController:(IGListSectionController *)contro
     return attributes;
 }
 
-- (void)mapCell:(UICollectionViewCell *)cell toSectionController:(IGListSectionController<IGListSectionType> *)sectionController {
+- (void)mapView:(UICollectionReusableView *)view toSectionController:(IGListSectionController<IGListSectionType> *)sectionController {
     IGAssertMainThread();
-    IGParameterAssert(cell != nil);
+    IGParameterAssert(view != nil);
     IGParameterAssert(sectionController != nil);
-    [_cellSectionControllerMap setObject:sectionController forKey:cell];
+    [_viewSectionControllerMap setObject:sectionController forKey:view];
 }
 
-- (nullable IGListSectionController<IGListSectionType> *)sectionControllerForCell:(UICollectionViewCell *)cell {
+- (nullable IGListSectionController<IGListSectionType> *)sectionControllerForView:(UICollectionReusableView *)view {
     IGAssertMainThread();
-    return [_cellSectionControllerMap objectForKey:cell];
+    return [_viewSectionControllerMap objectForKey:view];
 }
 
-- (void)removeMapForCell:(UICollectionViewCell *)cell {
+- (void)removeMapForView:(UICollectionReusableView *)view {
     IGAssertMainThread();
-    [_cellSectionControllerMap removeObjectForKey:cell];
+    [_viewSectionControllerMap removeObjectForKey:view];
 }
 
 #pragma mark - UICollectionViewDataSource
@@ -669,7 +669,7 @@ - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cell
     IGAssert(cell != nil, @"Returned a nil cell at indexPath <%@> from section controller: <%@>", indexPath, sectionController);
 
     // associate the section controller with the cell so that we know which section controller is using it
-    [self mapCell:cell toSectionController:sectionController];
+    [self mapView:cell toSectionController:sectionController];
 
     return cell;
 }
@@ -679,6 +679,10 @@ - (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView
     id <IGListSupplementaryViewSource> supplementarySource = [sectionController supplementaryViewSource];
     UICollectionReusableView *view = [supplementarySource viewForSupplementaryElementOfKind:kind atIndex:indexPath.item];
     IGAssert(view != nil, @"Returned a nil supplementary view at indexPath <%@> from section controller: <%@>, supplementary source: <%@>", indexPath, sectionController, supplementarySource);
+
+    // associate the section controller with the cell so that we know which section controller is using it
+    [self mapView:view toSectionController:sectionController];
+
     return view;
 }
 
@@ -703,12 +707,12 @@ - (void)collectionView:(UICollectionView *)collectionView willDisplayCell:(UICol
         [collectionViewDelegate collectionView:collectionView willDisplayCell:cell forItemAtIndexPath:indexPath];
     }
 
-    IGListSectionController <IGListSectionType> *sectionController = [self sectionControllerForCell:cell];
+    IGListSectionController <IGListSectionType> *sectionController = [self sectionControllerForView:cell];
     // if the section controller relationship was destroyed, reconnect it
     // this happens with iOS 10 UICollectionView display range changes
     if (sectionController == nil) {
         sectionController = [self sectionControllerForSection:indexPath.section];
-        [self mapCell:cell toSectionController:sectionController];
+        [self mapView:cell toSectionController:sectionController];
     }
 
     id object = [self.sectionMap objectForSection:indexPath.section];
@@ -726,12 +730,42 @@ - (void)collectionView:(UICollectionView *)collectionView didEndDisplayingCell:(
         [collectionViewDelegate collectionView:collectionView didEndDisplayingCell:cell forItemAtIndexPath:indexPath];
     }
 
-    IGListSectionController <IGListSectionType> *sectionController = [self sectionControllerForCell:cell];
+    IGListSectionController <IGListSectionType> *sectionController = [self sectionControllerForView:cell];
     [self.displayHandler didEndDisplayingCell:cell forListAdapter:self sectionController:sectionController indexPath:indexPath];
     [self.workingRangeHandler didEndDisplayingItemAtIndexPath:indexPath forListAdapter:self];
 
     // break the association between the cell and the section controller
-    [self removeMapForCell:cell];
+    [self removeMapForView:cell];
+}
+
+- (void)collectionView:(UICollectionView *)collectionView willDisplaySupplementaryView:(UICollectionReusableView *)view forElementKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath {
+    id<UICollectionViewDelegate> collectionViewDelegate = self.collectionViewDelegate;
+    if ([collectionViewDelegate respondsToSelector:@selector(collectionView:willDisplaySupplementaryView:forElementKind:atIndexPath:)]) {
+        [collectionViewDelegate collectionView:collectionView willDisplaySupplementaryView:view forElementKind:elementKind atIndexPath:indexPath];
+    }
+
+    IGListSectionController <IGListSectionType> *sectionController = [self sectionControllerForView:view];
+    // if the section controller relationship was destroyed, reconnect it
+    // this happens with iOS 10 UICollectionView display range changes
+    if (sectionController == nil) {
+        sectionController = [self.sectionMap sectionControllerForSection:indexPath.section];
+        [self mapView:view toSectionController:sectionController];
+    }
+
+    id object = [self.sectionMap objectForSection:indexPath.section];
+    [self.displayHandler willDisplaySupplementaryView:view forListAdapter:self sectionController:sectionController object:object indexPath:indexPath];
+}
+
+- (void)collectionView:(UICollectionView *)collectionView didEndDisplayingSupplementaryView:(UICollectionReusableView *)view forElementOfKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath {
+    id<UICollectionViewDelegate> collectionViewDelegate = self.collectionViewDelegate;
+    if ([collectionViewDelegate respondsToSelector:@selector(collectionView:didEndDisplayingSupplementaryView:forElementOfKind:atIndexPath:)]) {
+        [collectionViewDelegate collectionView:collectionView didEndDisplayingSupplementaryView:view forElementOfKind:elementKind atIndexPath:indexPath];
+    }
+
+    IGListSectionController <IGListSectionType> *sectionController = [self sectionControllerForView:view];
+    [self.displayHandler didEndDisplayingSupplementaryView:view forListAdapter:self sectionController:sectionController indexPath:indexPath];
+
+    [self removeMapForView:view];
 }
 
 #pragma mark - UIScrollViewDelegate
@@ -806,7 +840,7 @@ - (__kindof UICollectionViewCell *)cellForItemAtIndex:(NSInteger)index
         // only return a cell if it belongs to the section controller
         // this association is created in -collectionView:cellForItemAtIndexPath:
         UICollectionViewCell *cell = [self.collectionView cellForItemAtIndexPath:indexPath];
-        if ([self sectionControllerForCell:cell] == sectionController) {
+        if ([self sectionControllerForView:cell] == sectionController) {
             return cell;
         }
     }

Source/Internal/IGListDisplayHandler.h

@@ -22,12 +22,12 @@ IGLK_SUBCLASSING_RESTRICTED
 @interface IGListDisplayHandler : NSObject
 
 /**
- Tells the handler that a cell will be displayed in the IGListKit infra.
+ Tells the handler that a cell will be displayed in the IGListAdapter.
 
- @param cell              A cell that will display.
- @param listAdapter       The adapter managing the infra.
- @param sectionController The section controller the cell is in.
- @param object            The object associated with the section controller.
+ @param cell              A cell that will be displayed.
+ @param listAdapter       The adapter the cell will display in.
+ @param sectionController The section controller that manages the cell.
+ @param object            The object that powers the section controller.
  @param indexPath         The index path of the cell in the UICollectionView.
  */
 - (void)willDisplayCell:(UICollectionViewCell *)cell
@@ -37,18 +37,48 @@ IGLK_SUBCLASSING_RESTRICTED
               indexPath:(NSIndexPath *)indexPath;
 
 /**
- Tells the handler that a cell did end display in the IGListKit infra.
+ Tells the handler that a cell did end display in the IGListAdapter.
 
- @param cell              A cell that did end display.
- @param listAdapter       The adapter managing the infra.
- @param sectionController The section controller the cell is in.
+ @param cell              A cell that will be displayed.
+ @param listAdapter       The adapter the cell will display in.
+ @param sectionController The section controller that manages the cell.
  @param indexPath         The index path of the cell in the UICollectionView.
  */
 - (void)didEndDisplayingCell:(UICollectionViewCell *)cell
               forListAdapter:(IGListAdapter *)listAdapter
            sectionController:(IGListSectionController<IGListSectionType> *)sectionController
                    indexPath:(NSIndexPath *)indexPath;
 
+
+/**
+ Tells the handler that a supplementary view will be displayed in the IGListAdapter.
+
+ @param view              A supplementary view that will be displayed.
+ @param listAdapter       The adapter the supplementary view will display in.
+ @param sectionController The section controller that manages the supplementary view.
+ @param object            The object that powers the section controller.
+ @param indexPath         The index path of the supplementary view in the UICollectionView.
+ */
+- (void)willDisplaySupplementaryView:(UICollectionReusableView *)view
+                      forListAdapter:(IGListAdapter *)listAdapter
+                   sectionController:(IGListSectionController<IGListSectionType> *)sectionController
+                              object:(id)object
+                           indexPath:(NSIndexPath *)indexPath;
+
+
+/**
+ Tells the handler that a supplementary view did end display in the IGListAdapter.
+
+ @param view              A supplementary view that will be displayed.
+ @param listAdapter       The adapter the supplementary view will display in.
+ @param sectionController The section controller that manages the supplementary view.
+ @param indexPath         The index path of the supplementary view in the UICollectionView.
+ */
+- (void)didEndDisplayingSupplementaryView:(UICollectionReusableView *)view
+                           forListAdapter:(IGListAdapter *)listAdapter
+                        sectionController:(IGListSectionController<IGListSectionType> *)sectionController
+                                indexPath:(NSIndexPath *)indexPath;
+
 @end
 
 NS_ASSUME_NONNULL_END