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I have a navigation controller with two VCs. One VC is pushed onto the NavController, the other is presented on top of the NavController. The presented VC has a relatively complex animation involving a CAEmitter -> Animate birth rate down -> Fade out -> Remove. The pushed VC has an 'inputAccessoryView' and can become first responder. The expected behavior is open presented VC -> Emitter Emits pretty pictures -> emitter stops gracefully. The animation works perfectly. UNLESS I open pushed VC -> Leave -> go to presented VC. In this case when I open the presented VC the emitter emits pretty pictures -> they never stop. (Please do not ask me how long it took to figure this much out 🤬😔) The animation code in question is: let animation = CAKeyframeAnimation(keyPath: #keyPath(CAEmitterLayer.birthRate)) animation.duration = 1 animation.timingFunction = CAMediaTimingFunction(name: .easeIn) animation.values = [1, 0 , 0] animation.keyTimes = [0, 0.5, 1] animation.fillMode = .forwards animation.isRemovedOnCompletion = false emitter.beginTime = CACurrentMediaTime() let now = Date() CATransaction.begin() CATransaction.setCompletionBlock { [weak self] in print("fade beginning -- delta: \(Date().timeIntervalSince(now))") let transition = CATransition() transition.delegate = self transition.type = .fade transition.duration = 1 transition.timingFunction = CAMediaTimingFunction(name: .easeOut) transition.setValue(emitter, forKey: kKey) transition.isRemovedOnCompletion = false emitter.add(transition, forKey: nil) emitter.opacity = 0 } emitter.add(animation, forKey: nil) CATransaction.commit() The delegate method is: extension PresentedVC: CAAnimationDelegate { func animationDidStop(_ anim: CAAnimation, finished flag: Bool) { if let emitter = anim.value(forKey: kKey) as? CALayer { emitter.removeAllAnimations() emitter.removeFromSuperlayer() } else { } } } Here is the pushed VC: class PushedVC: UIViewController { override var canBecomeFirstResponder: Bool { return true } override var canResignFirstResponder: Bool { return true } override var inputAccessoryView: UIView? { return UIView() } } So to reiterate - If I push pushedVC onto the navController, pop it, present PresentedVC the emitters emit, but then the call to emitter.add(animation, forKey: nil) is essentially ignored. The emitter just keeps emitting. Here are some sample happy print statements from the completion block: fade beginning -- delta: 1.016232967376709 fade beginning -- delta: 1.0033869743347168 fade beginning -- delta: 1.0054619312286377 fade beginning -- delta: 1.0080779790878296 fade beginning -- delta: 1.0088880062103271 fade beginning -- delta: 0.9923020601272583 fade beginning -- delta: 0.99943196773529 Here are my findings: The issue presents only when the pushed VC has an inputAccessoryView AND canBecomeFirstResponder is true It does not matter if the inputAccessoryView is UIKit or custom, has size, is visible, or anything. When I dismiss PresentedVC the animation is completed and the print statements show. Here are some unhappy print examples: fade beginning -- delta: 5.003802061080933 fade beginning -- delta: 5.219511032104492 fade beginning -- delta: 5.73025906085968 fade beginning -- delta: 4.330522060394287 fade beginning -- delta: 4.786169052124023 CATransaction.flush() does not fix anything Removing the entire CATransaction block and just calling emitter.add(animation, forKey: nil) similarly does nothing - the birth rate decrease animation does not happen I am having trouble creating a simple demo project where the issue is reproducible (it is 100% reproducible in my code, the entirety of which I'm not going to link here) so I think getting a "solution" is unrealistic. What I would love is if anyone had any suggestions on where else to look? Any ways to debug CAAnimation? I think if I can solve the last bullet - emitter.add(animation, forKey: nil) called w/o a CATransaction - I can break this whole thing. Why would a CAAnimation added directly to the layer which is visible and doing stuff refuse to run?

I am trying to implement (in Swift/iOS) Resumable Uploads in a similar fashion to this wwdc23 video Fortunately there is an open source solution to do most of the work! The issue is that background URLSessions seem to have a mind of their own? Basically the gist of the resumable uploads is that an upload will progress to the best of its ability, and then when it fails it's supposed to run a HEAD request to see how much of the file has been written, and then resume uploading from the last good offset. I can not for the life of me get this to work in a "real life" scenario. Something as trivial as leaving wifi for cell causes everything to break. And this isn't that crazy of a scenario! It's totally reasonable to expect a user to do some stuff before they leave the house, and then take their phone and drive away. The WiFI connection will drop and the user will switch to cell. As it is right now the way URLSession handles things is that the initial task fails, but instead of loud, hard failing it quietly, softly fails and then as soon as there is network again the request is completely restarted. This breaks everything. Either the original request timed out and attempting to re-write the entire file fails because the offsets dont match any more (prev had some non-0 offset, new has 0 offset, non-zero != 0), or it fails because there are now two requests who think they have the appropriate offsets and everything gets out of sync. My understanding is that iOS 17 has implemented resumable uploads in a nice way, but how to manage for all the users who don't immediately upgrade? Is there a way to say "Hey URLSession, I know you want to immediately restart this request that failed due to the network disappearing and normally this is what people want, but maybe just cancel that last request that failed and then run this little handler to see where you should really start from and then start from there" My guess is that this is impossible because it needs to run in the background and iOS doesn't like letting apps run when they're not supposed to be? That's why this all had to be baked into iOS17. Just looking for anyone who has any idea how to handle this.

Trying to get a "sticky cell" that will orthogonally scroll with the section, but only partially, leaving the trailing end exposed until scrolled backwards. Demo Code: https://developer.apple.com/documentation/uikit/views_and_controls/collection_views/implementing_modern_collection_views (Download the project) Open: Modern Collection Views > Compositional Layout > Advanced layouts View Controllers > OrthogonalScrollBehaviorViewController.swift Replace func createLayout() -> UICollectionViewLayout { ... } With func createLayout() -> UICollectionViewLayout { let config = UICollectionViewCompositionalLayoutConfiguration() config.interSectionSpacing = 20 let layout = UICollectionViewCompositionalLayout(sectionProvider: { (sectionIndex: Int, layoutEnvironment: NSCollectionLayoutEnvironment) -> NSCollectionLayoutSection? in guard let sectionKind = SectionKind(rawValue: sectionIndex) else { fatalError("unknown section kind") } let leadingItem = NSCollectionLayoutItem(layoutSize: NSCollectionLayoutSize( widthDimension: .fractionalWidth(0.5), heightDimension: .fractionalHeight(0.5))) let orthogonallyScrolls = sectionKind.orthogonalScrollingBehavior() != .none let containerGroup = NSCollectionLayoutGroup.horizontal( layoutSize: NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0), heightDimension: .fractionalHeight(0.4)), subitems: [leadingItem]) let section = NSCollectionLayoutSection(group: containerGroup) section.orthogonalScrollingBehavior = sectionKind.orthogonalScrollingBehavior() section.visibleItemsInvalidationHandler = { (items, offset, env) in let buffer: CGFloat = 50 for item in items { if item.indexPath.item == 0 { item.zIndex = 25 let w = item.frame.width if offset.x >= (w - buffer) { item.transform = CGAffineTransform(translationX: offset.x - (w - buffer), y: 0) } else { item.transform = .identity } } else { item.zIndex = -item.indexPath.item } } } let sectionHeader = NSCollectionLayoutBoundarySupplementaryItem( layoutSize: NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0), heightDimension: .estimated(44)), elementKind: OrthogonalScrollBehaviorViewController.headerElementKind, alignment: .top) section.boundarySupplementaryItems = [sectionHeader] return section }, configuration: config) return layout } As you can see it works perfectly RIGHT UP to where the cell is now "offscreen" according to its bounds (even though it is still clearly visible on screen) and it disappears. I have also tried using a custom UICollectionViewCompositionalLayout that makes sure the sticky element has an attribute in layoutAttributesForElements(in rect: CGRect), exactly the same results: As soon as the 'bounds' are offscreen the cell is removed even if the frame is very clearly still on screen.

How are developers supposed to support interactive reordering of custom cells in UICollectionViews that use UICollectionViewDiffableDataSource? collectionView.beginInteractiveMovementForItem(at: iPath) collectionView.updateInteractiveMovementTargetPosition(target) collectionView.endInteractiveMovement() Will work maybe 70% of the time, but the other 30% of the time when calling endInteractiveMovement() the dataSource.snapshot does not properly reflect the updated state. Obviously there is a way to make this work if we use UICollectionViewListCells and the .reorder accessory, but that's not an acceptable solution. Please advise.

I am getting crazy "illegal instruction: 4" errors all over the place. Carthage can't update because it is getting this error I can't archive because my old carthage dependencies are getting this error All of this started happening after switching to swift 5.2.4 How can I revert to swift 5.2.3? Alternative solutions are also welcome.

Hello all,Here is a stack overflow of my question if you want to just skip to there:https://stackoverflow.com/questions/60049577/corelocationmanager-never-pausesI'll ask here as well - My app has location services always on, it's eating up a lot of battery overnight. Trying to figure out why as CLLocationManager is set to pause, but it's not pausing?Relevant code is at the SO link, I'll post it here if people want. Long and short is that I put my phone down for an hour, didn't touch my phone, and watched the logs and location services NEVER paused. I think this has been happening since iOS 13? I'm more than able to pause location services myself, but my understanding was that Apple and iOS would automatically pause them? It definitely was pausing at one point but it's not any more. I'm wondering if I have something configured wrong? Any and all suggestions or advice is welcome, thanks.