IGListAdapter support for scrollViewDidEndDecelerating

CHANGELOG.md

@@ -21,6 +21,7 @@ The changelog for `IGListKit`. Also see the [releases](https://github.com/instag
 - Added `-[IGListCollectionContext selectItemAtIndex:]` Select an item through IGListCollectionContext like `-[IGListCollectionContext deselectItemAtIndex:]`. [Marvin Nazari](https://github.com/MarvinNazari) (tbd)
 
 - Added horizontal scrolling support to `IGListCollectionViewLayout`. [Peter Edmonston](https://github.com/edmonston)  [(#857)](https://github.com/Instagram/IGListKit/pull/857)
+- Added support for scrollViewDidEndDecelerating to `IGListAdapter`. [Phil Larson](https://github.com/plarson) [(#899)](https://github.com/Instagram/IGListKit/pull/899)
 
 3.0.0
 -----

Source/IGListAdapter.m

@@ -715,6 +715,17 @@ - (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL
     }
 }
 
+- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
+    // forward this method to the delegate b/c this implementation will steal the message from the proxy
+    id<UIScrollViewDelegate> scrollViewDelegate = self.scrollViewDelegate;
+    if ([scrollViewDelegate respondsToSelector:@selector(scrollViewDidEndDecelerating:)]) {
+        [scrollViewDelegate scrollViewDidEndDecelerating:scrollView];
+    }
+    NSArray<IGListSectionController *> *visibleSectionControllers = [self visibleSectionControllers];
+    for (IGListSectionController *sectionController in visibleSectionControllers) {
+        [[sectionController scrollDelegate] listAdapter:self didEndDeceleratingSectionController:sectionController];
+    }
+}
 
 #pragma mark - IGListCollectionContext
 

Source/IGListScrollDelegate.h

@@ -46,6 +46,14 @@ NS_SWIFT_NAME(ListScrollDelegate)
  */
 - (void)listAdapter:(IGListAdapter *)listAdapter didEndDraggingSectionController:(IGListSectionController *)sectionController willDecelerate:(BOOL)decelerate;
 
+/**
+ Tells the delegate that the section controller did end decelerating on screen.
+
+ @param listAdapter The list adapter whose collection view ended decelerating.
+ @param sectionController The visible section controller that ended decelerating.
+ */
+- (void)listAdapter:(IGListAdapter *)listAdapter didEndDeceleratingSectionController:(IGListSectionController *)sectionController;
+
 @end
 
 NS_ASSUME_NONNULL_END

Source/IGListStackedSectionController.m

@@ -416,6 +416,12 @@ - (void)listAdapter:(IGListAdapter *)listAdapter didEndDraggingSectionController
     }
 }
 
+- (void)listAdapter:(IGListAdapter *)listAdapter didEndDeceleratingSectionController:(IGListSectionController *)sectionController {
+    for (IGListSectionController *childSectionController in self.sectionControllers) {
+        [[childSectionController scrollDelegate] listAdapter:listAdapter didEndDeceleratingSectionController:childSectionController];
+    }
+}
+
 #pragma mark - IGListWorkingRangeDelegate
 
 - (void)listAdapter:(IGListAdapter *)listAdapter sectionControllerWillEnterWorkingRange:(IGListSectionController *)sectionController {

Source/Internal/IGListAdapterProxy.m

@@ -31,7 +31,8 @@ static BOOL isInterceptedSelector(SEL sel) {
             // UIScrollViewDelegate
             sel == @selector(scrollViewDidScroll:) ||
             sel == @selector(scrollViewWillBeginDragging:) ||
-            sel == @selector(scrollViewDidEndDragging:willDecelerate:)
+            sel == @selector(scrollViewDidEndDragging:willDecelerate:) ||
+            sel == @selector(scrollViewDidEndDecelerating:)
             );
 }