Provide support for context menus (#1)

CHANGELOG.md

@@ -61,6 +61,8 @@ The changelog for `IGListKit`. Also see the [releases](https://github.com/instag
 
 ### Enhancements
 
+- Added support for iOS 13 Context Menus with `contextMenuConfigurationForItemAt` method. [Jérôme B.](https://github.com/jjbourdev) [(#1430)](https://github.com/Instagram/IGListKit/pull/1430).
+
 - 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/) 

Examples/Examples-iOS/IGListKitExamples/SectionControllers/MonthSectionController.swift

@@ -92,4 +92,26 @@ final class MonthSectionController: ListBindingSectionController<ListDiffable>,
 
     func sectionController(_ sectionController: ListBindingSectionController<ListDiffable>, didUnhighlightItemAt index: Int, viewModel: Any) {}
 
+    @available(iOS 13.0, *)
+    func sectionController(_ sectionController: ListBindingSectionController<ListDiffable>, contextMenuConfigurationForItemAt index: Int, point: CGPoint, viewModel: Any) -> UIContextMenuConfiguration? {
+      return UIContextMenuConfiguration(identifier: nil, previewProvider: nil) { _ in
+          // Create an action for sharing
+        let share = UIAction(title: "Share", image: UIImage(systemName: "square.and.arrow.up")) { _ in
+            // Show share sheet
+        }
+
+        // Create an action for copy
+        let rename = UIAction(title: "Copy", image: UIImage(systemName: "doc.on.doc")) { _ in
+            // Perform copy
+        }
+
+        // Create an action for delete with destructive attributes (highligh in red)
+        let delete = UIAction(title: "Delete", image: UIImage(systemName: "trash"), attributes: .destructive) { _ in
+            // Perform delete
+        }
+
+        // Create a UIMenu with all the actions as children
+        return UIMenu(title: "", children: [share, rename, delete])
+    }
+  }
 }

Source/IGListKit/IGListSectionController.h

@@ -120,6 +120,40 @@ NS_SWIFT_NAME(ListSectionController)
  */
 - (void)didUnhighlightItemAtIndex:(NSInteger)index;
 
+/**
+ Tells the section controller that the cell has requested a menu configuration.
+ 
+ @param index The index of the cell that requested the menu.
+ @param point The point of the tap on the cell.
+ 
+ @return An object that conforms to `UIContextMenuConfiguration`
+ 
+ @note The default implementation does nothing. **Calling super is not required.**
+ */
+- (UIContextMenuConfiguration * _Nullable)contextMenuConfigurationForItemAtIndex:(NSInteger)index point:(CGPoint)point API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos);
+
+/**
+ Tells the section controller that the cell has requested a preview for context menu highlight.
+ 
+ @param configuration Context menu configuration.
+ 
+ @return An object that conforms to `UITargetedPreview`
+ 
+ @note The default implementation does nothing. **Calling super is not required.**
+ */
+- (UITargetedPreview * _Nullable)previewForHighlightingContextMenuWithConfiguration:(UIContextMenuConfiguration *)configuration API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos);
+
+/**
+ Tells the section controller that the cell has requested a preview for context menu dismiss.
+ 
+ @param configuration Context menu configuration.
+ 
+ @return An object that conforms to `UITargetedPreview`
+ 
+ @note The default implementation does nothing. **Calling super is not required.**
+ */
+- (UITargetedPreview * _Nullable)previewForDismissingContextMenuWithConfiguration:(UIContextMenuConfiguration *)configuration API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos);
+
 /**
  Identifies whether an object can be moved through interactive reordering.
 

Source/IGListKit/IGListSectionController.m

@@ -97,6 +97,18 @@ - (void)didHighlightItemAtIndex:(NSInteger)index {}
 
 - (void)didUnhighlightItemAtIndex:(NSInteger)index {}
 
+- (UIContextMenuConfiguration * _Nullable)contextMenuConfigurationForItemAtIndex:(NSInteger)index point:(CGPoint)point {
+    return nil;
+}
+
+- (UITargetedPreview * _Nullable)previewForHighlightingContextMenuWithConfiguration:(UIContextMenuConfiguration *)configuration {
+    return nil;
+}
+
+- (UITargetedPreview * _Nullable)previewForDismissingContextMenuWithConfiguration:(UIContextMenuConfiguration *)configuration {
+    return nil;
+}
+
 - (BOOL)canMoveItemAtIndex:(NSInteger)index {
     return NO;
 }

Source/IGListKit/Internal/IGListAdapter+UICollectionView.m

@@ -18,6 +18,12 @@
 
 #import "IGListAdapterInternal.h"
 
+@interface IGListAdapter ()
+
+@property (nonatomic, strong) NSMapTable *configurationToSectionController;
+
+@end
+
 @implementation IGListAdapter (UICollectionView)
 
 #pragma mark - UICollectionViewDataSource
@@ -269,6 +275,47 @@ - (void)collectionView:(UICollectionView *)collectionView didUnhighlightItemAtIn
     [sectionController didUnhighlightItemAtIndex:indexPath.item];
 }
 
+#if !TARGET_OS_TV
+- (UIContextMenuConfiguration *)collectionView:(UICollectionView *)collectionView contextMenuConfigurationForItemAtIndexPath:(NSIndexPath *)indexPath point:(CGPoint)point API_AVAILABLE(ios(13.0)) {
+    // forward this method to the delegate b/c this implementation will steal the message from the proxy
+    id<UICollectionViewDelegate> collectionViewDelegate = self.collectionViewDelegate;
+    if ([collectionViewDelegate respondsToSelector:@selector(collectionView:contextMenuConfigurationForItemAtIndexPath:point:)]) {
+        return [collectionViewDelegate collectionView:collectionView contextMenuConfigurationForItemAtIndexPath:indexPath point:point];
+    }
+
+    IGListSectionController * sectionController = [self sectionControllerForSection:indexPath.section];
+
+    UIContextMenuConfiguration *configuration = [sectionController contextMenuConfigurationForItemAtIndex:indexPath.item point:point];
+    if (configuration) {
+        if (!self.configurationToSectionController) {
+            self.configurationToSectionController = [NSMapTable weakToWeakObjectsMapTable];
+        }
+        [self.configurationToSectionController setObject:configuration forKey:sectionController];
+    }
+    return nil;
+}
+
+- (UITargetedPreview *)collectionView:(UICollectionView *)collectionView previewForHighlightingContextMenuWithConfiguration:(UIContextMenuConfiguration *)configuration  API_AVAILABLE(ios(13.0)){
+    id<UICollectionViewDelegate> collectionViewDelegate = self.collectionViewDelegate;
+    if ([collectionViewDelegate respondsToSelector:@selector(collectionView:previewForHighlightingContextMenuWithConfiguration:)]) {
+        return [collectionViewDelegate collectionView:collectionView previewForHighlightingContextMenuWithConfiguration:configuration];
+    }
+
+    IGListSectionController * sectionController = [self.configurationToSectionController objectForKey:configuration];
+    return [sectionController previewForHighlightingContextMenuWithConfiguration:configuration];
+}
+
+- (UITargetedPreview *)collectionView:(UICollectionView *)collectionView previewForDismissingContextMenuWithConfiguration:(UIContextMenuConfiguration *)configuration  API_AVAILABLE(ios(13.0)){
+    id<UICollectionViewDelegate> collectionViewDelegate = self.collectionViewDelegate;
+    if ([collectionViewDelegate respondsToSelector:@selector(collectionView:previewForDismissingContextMenuWithConfiguration:)]) {
+        return [collectionViewDelegate collectionView:collectionView previewForDismissingContextMenuWithConfiguration:configuration];
+    }
+
+    IGListSectionController * sectionController = [self.configurationToSectionController objectForKey:configuration];
+    return [sectionController previewForDismissingContextMenuWithConfiguration:configuration];
+}
+#endif
+
 #pragma mark - UICollectionViewDelegateFlowLayout
 
 - (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {

Source/IGListKit/Internal/IGListAdapterProxy.m

@@ -33,6 +33,9 @@ static BOOL isInterceptedSelector(SEL sel) {
             sel == @selector(collectionView:didDeselectItemAtIndexPath:) ||
             sel == @selector(collectionView:didHighlightItemAtIndexPath:) ||
             sel == @selector(collectionView:didUnhighlightItemAtIndexPath:) ||
+            sel == @selector(collectionView:contextMenuConfigurationForItemAtIndexPath:point:) ||
+            sel == @selector(collectionView:previewForHighlightingContextMenuWithConfiguration:) ||
+            sel == @selector(collectionView:previewForDismissingContextMenuWithConfiguration:) ||
             // UICollectionViewDelegateFlowLayout
             sel == @selector(collectionView:layout:sizeForItemAtIndexPath:) ||
             sel == @selector(collectionView:layout:insetForSectionAtIndex:) ||

Tests/IGListAdapterTests.m

@@ -1339,7 +1339,7 @@ - (void)test_whenUnhighlightingCell_thatCollectionViewDelegateReceivesMethod {
     [mockDelegate verify];
 }
 
-- (void)test_whenUnlighlightingCell_thatSectionControllerReceivesMethod {
+- (void)test_whenUnhighlightingCell_thatSectionControllerReceivesMethod {
     self.dataSource.objects = @[@0, @1, @2];
     [self.adapter reloadDataWithCompletion:nil];
 
@@ -1357,6 +1357,40 @@ - (void)test_whenUnlighlightingCell_thatSectionControllerReceivesMethod {
     XCTAssertFalse(s2.wasUnhighlighted);
 }
 
+- (void)test_whenContextMenuAskedCell_thatCollectionViewDelegateReceivesMethod API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos) {
+    self.dataSource.objects = @[@0, @1, @2];
+    [self.adapter reloadDataWithCompletion:nil];
+
+    id mockDelegate = [OCMockObject mockForProtocol:@protocol(UICollectionViewDelegate)];
+    self.adapter.collectionViewDelegate = mockDelegate;
+
+    NSIndexPath *indexPath = [NSIndexPath indexPathForItem:0 inSection:0];
+    [[mockDelegate expect] collectionView:self.collectionView contextMenuConfigurationForItemAtIndexPath:indexPath point:CGPointZero];
+
+    // simulates the collectionview telling its delegate that it needs the context menu configuration
+    [self.adapter collectionView:self.collectionView contextMenuConfigurationForItemAtIndexPath:indexPath point:CGPointZero];
+
+    [mockDelegate verify];
+}
+
+- (void)test_whenContextMenuAskedCell_thatSectionControllerReceivesMethod API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos) {
+    self.dataSource.objects = @[@0, @1, @2];
+    [self.adapter reloadDataWithCompletion:nil];
+
+    NSIndexPath *indexPath = [NSIndexPath indexPathForItem:0 inSection:0];
+
+    // simulates the collectionview telling its delegate that it needs the context menu configuration
+    [self.adapter collectionView:self.collectionView contextMenuConfigurationForItemAtIndexPath:indexPath point:CGPointZero];
+
+    IGListTestSection *s0 = [self.adapter sectionControllerForObject:@0];
+    IGListTestSection *s1 = [self.adapter sectionControllerForObject:@1];
+    IGListTestSection *s2 = [self.adapter sectionControllerForObject:@2];
+
+    XCTAssertTrue(s0.requestedContextMenu);
+    XCTAssertFalse(s1.requestedContextMenu);
+    XCTAssertFalse(s2.requestedContextMenu);
+}
+
 - (void)test_whenDataSourceDoesntHandleObject_thatObjectIsDropped {
     // IGListTestAdapterDataSource does not handle NSStrings
     self.dataSource.objects = @[@1, @"dog", @2];

Tests/IGListBindingSectionControllerTests.m

@@ -190,6 +190,15 @@ - (void)test_whenUnhighlightingCell_thatCorrectViewModelUnhighlighted {
     XCTAssertEqualObjects(section.unhighlightedViewModel, @"seven");
 }
 
+- (void)test_whenContextMenuAskedCell_thatCorrectViewModelRetrieved API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos) {
+    [self setupWithObjects:@[
+                             [[IGTestDiffingObject alloc] initWithKey:@1 objects:@[@7, @"seven"]],
+                             ]];
+    [self.adapter collectionView:self.collectionView contextMenuConfigurationForItemAtIndexPath:[NSIndexPath indexPathForItem:1 inSection:0] point:CGPointZero];
+    IGTestDiffingSectionController *section = [self.adapter sectionControllerForObject:self.dataSource.objects.firstObject];
+    XCTAssertEqualObjects(section.contextMenuViewModel, @"seven");
+}
+
 - (void)test_whenDeselectingCell_withoutImplementation_thatNoOps {
     [self setupWithObjects:@[
                              [[IGTestDiffingObject alloc] initWithKey:@1 objects:@[@7, @"seven"]],

Tests/Objects/IGListTestSection.h

@@ -19,5 +19,6 @@
 @property (nonatomic, assign) BOOL wasHighlighted;
 @property (nonatomic, assign) BOOL wasUnhighlighted;
 @property (nonatomic, assign) BOOL wasDisplayed;
+@property (nonatomic, assign) BOOL requestedContextMenu;
 
 @end

Tests/Objects/IGListTestSection.m

@@ -60,6 +60,11 @@ - (void)didUnhighlightItemAtIndex:(NSInteger)index {
     self.wasUnhighlighted = YES;
 }
 
+- (UIContextMenuConfiguration * _Nullable)contextMenuConfigurationForItemAtIndex:(NSInteger)index point:(CGPoint)point {
+  self.requestedContextMenu = YES;
+  return nil;
+}
+
 #pragma mark - IGListDisplayDelegate
 
 - (void)listAdapter:(IGListAdapter *)listAdapter willDisplaySectionController:(IGListSectionController *)sectionController {

Tests/Objects/IGTestBindingWithoutDeselectionDelegate.m

@@ -31,4 +31,12 @@ - (void)sectionController:(nonnull IGListBindingSectionController *)sectionContr
                 viewModel:(nonnull id)viewModel {
 }
 
+
+- (UIContextMenuConfiguration * _Nullable)sectionController:(nonnull IGListBindingSectionController *)sectionController
+                    contextMenuConfigurationForItemAtIndex:(NSInteger)index
+                                                     point:(CGPoint)point
+                                                 viewModel:(nonnull id)viewModel API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos) {
+  return nil;
+}
+
 @end

Tests/Objects/IGTestDiffingSectionController.h

@@ -13,5 +13,6 @@
 @property (nonatomic, strong) id deselectedViewModel;
 @property (nonatomic, strong) id highlightedViewModel;
 @property (nonatomic, strong) id unhighlightedViewModel;
+@property (nonatomic, strong) id contextMenuViewModel;
 
 @end

Tests/Objects/IGTestDiffingSectionController.m

@@ -65,4 +65,9 @@ - (void)sectionController:(IGListBindingSectionController *)sectionController di
     self.unhighlightedViewModel = viewModel;
 }
 
+- (UIContextMenuConfiguration * _Nullable)sectionController:(IGListBindingSectionController *)sectionController contextMenuConfigurationForItemAtIndex:(NSInteger)index point:(CGPoint)point viewModel:(id)viewModel API_AVAILABLE(ios(13.0)) API_UNAVAILABLE(tvos) {
+  self.contextMenuViewModel = viewModel;
+  return nil;
+}
+
 @end