Merge pull request #996 from planetary-social/fix-nsinternalconsisten…

…cyexpection-in-pagednotedatasource

Probably fix crash on home feed

.gitignore

@@ -83,3 +83,4 @@ fastlane/screenshots/**/*.png
 fastlane/test_output
 
 .idea
+.vscode

CHANGELOG.md

@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Updated dark theme colors for card backgrounds, primary text, and secondary text.
 - Added a new UI for replying to messages that allows attaching images and setting an expiration date.
 - Fixed an issue where Profile pages could display little or no content.
+- Fixed a crash that often occurred after opening the app.
 
 ## [0.1.7] - 2024-03-21Z
 

Nos.xcodeproj/project.pbxproj

@@ -1241,12 +1241,12 @@
 		C9DEC0042989477A0078B43A /* Fixtures */ = {
 			isa = PBXGroup;
 			children = (
-				C94B2D172B17F5EC002104B6 /* sample_repost.json */,
-				CD27177529A7C8B200AE8888 /* sample_replies.json */,
+				C9BD91882B61BBEF00FDA083 /* bad_contact_list.json */,
 				C9DEC005298947900078B43A /* sample_data.json */,
+				CD27177529A7C8B200AE8888 /* sample_replies.json */,
+				C94B2D172B17F5EC002104B6 /* sample_repost.json */,
 				C9ADB134299288230075E7F8 /* KeyFixture.swift */,
 				C90B16B72AFED96300CB4B85 /* URLExtensionTests.swift */,
-				C9BD91882B61BBEF00FDA083 /* bad_contact_list.json */,
 			);
 			path = Fixtures;
 			sourceTree = "<group>";

Nos/Controller/PagedNoteDataSource.swift

@@ -87,9 +87,14 @@ class PagedNoteDataSource<Header: View, EmptyPlaceholder: View>: NSObject, UICol
     // MARK: - UICollectionViewDataSource
 
     func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
-        let numberOfItems = fetchedResultsController.fetchedObjects?.count ?? 0
-        Log.debug("Number of items: \(numberOfItems) in section: \(section)")
-        return numberOfItems
+        let numberOfFetchedObjects = fetchedResultsController.fetchedObjects?.count ?? 0
+        // because we batch updates together to reduce animations but this function is called in between batches we
+        // need to account for the number of items queued for insertion or deletion. FetchedResultsController sees them
+        // but the collectionView doesn't yet.
+        let numberOfItemsInView = numberOfFetchedObjects - insertedIndexes.count + deletedIndexes.count
+        Log.debug("Number of items: \(numberOfFetchedObjects) in fetchedResultsController")
+        Log.debug("Number of items: \(numberOfItemsInView) in section: \(section)")
+        return numberOfItemsInView
     }
 
     func collectionView(
@@ -238,11 +243,15 @@ class PagedNoteDataSource<Header: View, EmptyPlaceholder: View>: NSObject, UICol
         Log.debug("controllerDidChangeContent started.")
         if !deletedIndexes.isEmpty { // it doesn't seem like this check should be necessary but it crashes otherwise
             Log.debug("deleting indexPaths: \(deletedIndexes)")
-            collectionView.deleteItems(at: deletedIndexes)
+            let deletedIndexesCopy = deletedIndexes
+            deletedIndexes = [] // clear indexes so numberOfItemsInSection can calculate the correct number
+            collectionView.deleteItems(at: deletedIndexesCopy)
         }
         if !insertedIndexes.isEmpty {
             Log.debug("inserting indexPaths: \(insertedIndexes)")
-            collectionView.insertItems(at: insertedIndexes)
+            let insertedIndexesCopy = insertedIndexes
+            insertedIndexes = [] // clear indexes so numberOfItemsInSection can calculate the correct number
+            collectionView.insertItems(at: insertedIndexesCopy)
         }
 
         Log.debug("moving indexes: \(movedIndexes)")