I have two section backgrounds for my compositional layout.
layout.register(
FollowingSectionBackgroundView.self,
forDecorationViewOfKind: FollowingCollectionViewController.sectionBackgroundDecorationFollowing)
layout.register(
BrowseSectionBackgroundView.self,
forDecorationViewOfKind: FollowingCollectionViewController.sectionBackgroundDecorationBrowse)
And I configure them like so in my UICollectionViewCompositonaLayoutClosure
if sectionIndex == 0 {
let sectionBackgroundDecoration = NSCollectionLayoutDecorationItem.background(
elementKind: FollowingCollectionViewController.sectionBackgroundDecorationFollowing)
section.decorationItems = [sectionBackgroundDecoration]
} else {
let sectionBackgroundDecoration = NSCollectionLayoutDecorationItem.background(
elementKind: FollowingCollectionViewController.sectionBackgroundDecorationBrowse)
section.decorationItems = [sectionBackgroundDecoration]
}
And this seems to be working just fine, however I have seen crashes uploaded that say:
Fatal Exception: NSInternalInconsistencyException
no UICollectionViewLayoutAttributes instance for -layoutAttributesForDecorationViewOfKind: section-background-browse at path <NSIndexPath: 0xfe6f76a7b11ddfee> {length = 2, path = 0 - 0}
The crash appears to happen when the user searches.
isSearching = true
let following = FollowingController.filterBrowse(with: filter).sorted { $0.name < $1.name }
var snapshot = NSDiffableDataSourceSnapshot<SectionLayoutKind, FollowingEntity>()
snapshot.appendSections([.browse])
snapshot.appendItems(following)
dataSource.apply(snapshot, animatingDifferences: true)
Im unable to reproduce this issue but just curious if anyone has run into this, and might have an idea for solving it.
nomspes
Users receive reputation points by contributing quality content to the forums.
Posts include post and replies published on the forums.
Post authors can mark replies as Accepted to indicate successful solutions.
Apple Developer Forums admins can mark replies as Apple Recommended to indicate an approved solution
Last seen
User for
From
San Francisco, CA, United States
Post
Replies
Boosts
Views
Activity
Why does returning nil from
UICollectionViewDiffableDataSource<FeedElement, Entity>(collectionView: collectionView) {
(collectionView: UICollectionView, indexPath: IndexPath, entity: Entity) -> UICollectionViewCell? in
result n "the collection view's data source did not return a valid cell from"
Isn't the UICollectionViewCell optional?
I can't seem to get UICollectionViewDataSourcePrefetching working with DiffableDatasource, my delegate methods are not being called. Do these work together?
		func viewDidLoad()
				....
collectionView.prefetchDataSource = self
collectionView.isPrefetchingEnabled = true
		}
extension ViewController: UICollectionViewDataSourcePrefetching {
func collectionView(_ collectionView: UICollectionView, prefetchItemsAt indexPaths: [IndexPath]) {
let urls: [URL] = indexPaths.compactMap { indexPath in
guard let displayableItem = dataSource.itemIdentifier(for: indexPath),
let itemViewModel = displayableItem.item as? ViewModel,
let image = itemViewModel.firstImageURL else {
return nil
}
return image
}
ATHLogging.log.critical("prefetching: \(urls)")
preheater.startPreheating(with: urls)
}
I have a crash happening when applying a snapshot. 9/10 times its seems to work.
When we re-fetch backend data, and apply the snapshot sometimes we get the follow crash
the view returned from -collectionView:viewForSupplementaryElementOfKind:atIndexPath (cover-edge-trailing-element-kind,<NSIndexPath: 0xf45fd089cda10b3f> {length = 2, path = 55 - 1}) was not retrieved by calling -dequeueReusableSupplementaryViewOfKind:withReuseIdentifier:forIndexPath: or is nil ((null))
We don't call this function, as it seems to be done by the diffable datasource.
Fatal Exception: NSInternalInconsistencyException
0	CoreFoundation								 0x1b75c2300 __exceptionPreprocess
1	libobjc.A.dylib								0x1b72d6c1c objc_exception_throw
2	CoreFoundation								 0x1b74bf1f8 +[_CFXNotificationTokenRegistration keyCallbacks]
3	Foundation										 0x1b7903998 -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:]
4	UIKitCore											0x1baf133dc -[UICollectionView _createPreparedSupplementaryViewForElementOfKind:atIndexPath:withLayoutAttributes:applyAttributes:]
5	UIKitCore											0x1baf2dc6c -[UICollectionView _viewAnimationsForCurrentUpdate]
6	UIKitCore											0x1baf31d68 __71-[UICollectionView _updateWithItems:tentativelyForReordering:animator:]_block_invoke.2004
7	UIKitCore											0x1bbbcf5d8 +[UIView(Animation) performWithoutAnimation:]
8	UIKitCore											0x1baf30f2c -[UICollectionView _updateWithItems:tentativelyForReordering:animator:]
9	UIKitCore											0x1baf2b488 -[UICollectionView _endItemAnimationsWithInvalidationContext:tentativelyForReordering:animator:]
10 UIKitCore											0x1baf32f4c -[UICollectionView _endUpdatesWithInvalidationContext:tentativelyForReordering:animator:]
11 UIKitCore											0x1baf332d0 -[UICollectionView _performBatchUpdates:completion:invalidationContext:tentativelyForReordering:animator:]
12 UIKitCore											0x1baf33100 -[UICollectionView _performBatchUpdates:completion:invalidationContext:tentativelyForReordering:]
13 UIKitCore											0x1baf3307c -[UICollectionView _performBatchUpdates:completion:invalidationContext:]
14 UIKitCore											0x1baf32fa8 -[UICollectionView performBatchUpdates:completion:]
15 UIKitCore											0x1baf41268 -[UICollectionView _performDiffableUpdate:]
16 UIKitCore											0x1baee7e6c -[_UIDiffableDataSourceViewUpdater _performUpdateWithCollectionViewUpdateItems:dataSourceSnapshotter:updateHandler:completion:]
17 UIKitCore											0x1baee10f4 -[__UIDiffableDataSource _commitNewDataSource:withViewUpdates:completion:]
18 UIKitCore											0x1baedc0c0 66-[UIDiffableDataSource applyDifferencesFromSnapshot:completion:]_block_invoke.154
19 UIKitCore											0x1baedc388 66-[UIDiffableDataSource applyDifferencesFromSnapshot:completion:]_block_invoke.183
20 libdispatch.dylib							0x1b726233c _dispatch_client_callout
21 libdispatch.dylib							0x1b726f1f4 _dispatch_lane_barrier_sync_invoke_and_complete
22 UIKitCore											0x1baedbba8 -[__UIDiffableDataSource applyDifferencesFromSnapshot:completion:]
23 UIKitCore											0x1baedcc68 -[__UIDiffableDataSource applyDifferencesFromSnapshot:animatingDifferences:completion:]
24 libswiftUIKit.dylib						0x1edef8030 UICollectionViewDiffableDataSource.apply(_:animatingDifferences:completion:)
25 theathletic-ios								0x105048b60 closure #1 in RealTimeContentsViewController.fetchData(with:newWatcher:) + 137 (RealTimeContentsViewController.swift:137)
26 theathletic-ios								0x10504b48c RealTimeContentsViewController.updateDataSource(for:completion:) + 265 (RealTimeContentsViewController.swift:265)
27 theathletic-ios	
Heres how we are registering, creating, and supplying the view
static let coverEdgeTrailingIdentifier = "cover-edge-trailing-element-kind"
collectionView.register(
CoverEdgeCollectionReusableView.self,
forSupplementaryViewOfKind: K.coverEdgeTrailingIdentifier,
withReuseIdentifier: CoverEdgeCollectionReusableView.reuseIdentifier)
dataSource.supplementaryViewProvider = { (
collectionView: UICollectionView,
kind: String,
indexPath: IndexPath) -> UICollectionReusableView? {
return collectionView.dequeueReusableSupplementaryView(
ofKind: kind,
withReuseIdentifier: CoverEdgeCollectionReusableView.reuseIdentifier,
for: indexPath) as! CoverEdgeCollectionReusableView
}
There is a black bar at the top of my Widget and I can't seem to figure out how to get rid of it.
struct A1EntryView : View {
var entry: Provider.Entry
var body: some View {
Text("Temp")
.frame(maxHeight: .infinity)
.background(Color(.red))
.ignoresSafeArea(.all)
}
}