Add shouldDeselectItemAtIndex to IGListSectionController

Summary: Add `shouldDeselectItemAtIndex:` to `IGListSectionController`. `shouldSelectItemAtIndex:` already exists, but its inverse does not.

Reviewed By: lorixx

Differential Revision: D34727371

fbshipit-source-id: ba4e0917380e1b3ff189dad7977ac5c1caa9b714

CHANGELOG.md

@@ -60,10 +60,11 @@ The changelog for `IGListKit`. Also see the [releases](https://github.com/instag
 ```
 
 ### Enhancements
+- Added `shouldDeselectItemAtIndex:` to `IGListSectionController` . [bladeofky](https://github.com/bladeofky)
 
 - Added `shouldSelectItemAtIndex:` to `IGListSectionController` . [dirtmelon](https://github.com/dirtmelon)
 
-- Added [Mac Catalyst](https://developer.apple.com/mac-catalyst/) support. [Petro Rovenskyy](https://github.com/3a4oT/) 
+- Added [Mac Catalyst](https://developer.apple.com/mac-catalyst/) support. [Petro Rovenskyy](https://github.com/3a4oT/)
 
 - Introduce `IGListSwiftKit`, with Swift refinements for `dequeueReusableCellOfClass` methods. [Koen Punt](https://github.com/koenpunt) [(#1388)](https://github.com/Instagram/IGListKit/pull/1388).
 
@@ -85,7 +86,7 @@ The changelog for `IGListKit`. Also see the [releases](https://github.com/instag
    - Schedules an update block (`dispatch_async`) only when needed, instead of scheduling on every single call to `-performUpdateWithCollectionViewBlock`.
    - Wraps each update in a `transaction` that can be easily cancelled.
    - Uses methods instead of blocks to make the callstack easier to read in crash reports.
-   - Unblocks `IGListExperimentBackgroundDiffing` 
+   - Unblocks `IGListExperimentBackgroundDiffing`
 
 ### Fixes
 

Source/IGListKit/IGListSectionController.h

@@ -84,6 +84,15 @@ NS_SWIFT_NAME(ListSectionController)
  */
 - (BOOL)shouldSelectItemAtIndex:(NSInteger)index;
 
+/**
+ Asks the section controller if the cell at the specified index path should be deselected
+
+ @param index The index of cell to be deselected.
+
+ @note The default implementation returns YES. **Calling super is not required.**
+ */
+- (BOOL)shouldDeselectItemAtIndex:(NSInteger)index;
+
 /**
  Tells the section controller that the cell at the specified index path was selected.
 

Source/IGListKit/IGListSectionController.m

@@ -89,6 +89,10 @@ void IGListSectionControllerPopThread(void) {
     return YES;
 }
 
+- (BOOL)shouldDeselectItemAtIndex:(NSInteger)index {
+    return YES;
+}
+
 - (void)didSelectItemAtIndex:(NSInteger)index {}
 
 - (void)didDeselectItemAtIndex:(NSInteger)index {}

Source/IGListKit/Internal/IGListAdapter+UICollectionView.m

@@ -127,6 +127,11 @@
     return [sectionController shouldSelectItemAtIndex:indexPath.item];
 }
 
+- (BOOL)collectionView:(UICollectionView *)collectionView shouldDeselectItemAtIndexPath:(NSIndexPath *)indexPath {
+    IGListSectionController * sectionController = [self sectionControllerForSection:indexPath.section];
+    return [sectionController shouldDeselectItemAtIndex:indexPath.item];
+}
+
 - (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {
     // forward this method to the delegate b/c this implementation will steal the message from the proxy
     id<UICollectionViewDelegate> collectionViewDelegate = self.collectionViewDelegate;