Core Animation

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Render, compose, and animate visual elements using Core Animation.

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iOS 26 Beta breaks scroll/gesture in SwiftUI chat (worked in iOS 18): Simultaneous gestures & ScrollViewReader issues
Hi all, After upgrading to the iOS 26 beta, the scrolling in my SwiftUI chat view is completely broken. The exact same code works perfectly on iOS 18. Context: I have a chat view using ScrollViewReader and a vertically-reversed ScrollView (with .rotationEffect(.degrees(180))). Each message row (MessageBubble) uses multiple simultaneousGesture handlers: Horizontal drag for swipe-to-reply (and other actions: pin, delete) Long press for showing popover/actions Vertical scroll for normal chat scrolling This was working great on iOS 18. In iOS 26 beta, the vertical scroll is either completely disabled, jittery, or hijacked by the message row’s drag gestures, even though .simultaneousGesture is used (see code below). Minimal Repro Sample MessageListView.swift swift Copy Edit ScrollViewReader { proxy in ScrollView(.vertical, showsIndicators: false) { LazyVStack(spacing: 0) { // ... grouped messages ForEach(...) { ... MessageBubble(...) // see below } Color.clear.frame(height: 8).id("BOTTOM_ANCHOR") } .padding(.horizontal, 4) .rotationEffect(.degrees(180)) } .rotationEffect(.degrees(180)) } MessageBubble.swift struct MessageBubble: View { // ... var body: some View { // horizontal swipe-to-reply gesture let dragGesture = DragGesture(minimumDistance: 10) // ... ZStack { // ... HStack { ... } // ... .simultaneousGesture( DragGesture(minimumDistance: 0) // for long press // ... ) .simultaneousGesture(dragGesture) // for horizontal swipe } // ... } }
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10
1.3k
Sep ’25
My app doesn't respond on iPhone Air iOS 26.1.
My app doesn't respond on iPhone Air iOS 26.1. After startup, my app shows the main view with a tab bar controller containing 4 navigation controllers. However, when a second-level view controller is pushed onto any navigation controller, the UI freezes and becomes unresponsive. The iPhone simulator running iOS 26.1 exhibits the same problem. The debug profile shows CPU usage at 100%. However, other devices and simulators do not have this problem.
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3d
Liquid Glass TabBar animations causes Hangs, bug with UIKitCore?
With iOS 26.1 we started seeing a bug that only appears on iPhone Air. This bug is visible with simulators too. I have tried so many different ways to fix the issue, but Instruments Profiler is pointing at UIKitCore. We load a tab bar, when the user attempts to switch a tab, the app hangs and never recovers. It happens right as the animation of the Glass bubble is in progress. I have tried a UIKit Tab bar, a SwiftUI Tab bar. I tore out AppDelegate and did a direct @main SwiftUI entry for my application. This issue appears with every tab bar instance I try. I attempted to disable LiquidGlass by utilizing this flag UIDesignRequiresCompatibility in my plist, but the flag seems to be ignored by the system. I am not sure what else to try. I have a trace file if that is helpful. What else can I upload? Here is what the code looks like. struct ContentView: View { @State private var selectedTab = 2 var body: some View { TabView(selection: $selectedTab) { Text("Profile") .tabItem { Label("Me", systemImage: "person") } .tag(0) Text("Training") .tabItem { Label("Training", systemImage: "calendar") } .tag(1) Text("Home") .tabItem { Label("Home", systemImage: "house") } .tag(2) Text("Goals") .tabItem { Label("Goals", systemImage: "target") } .tag(3) Text("Coach") .tabItem { Label("Coach", systemImage: "person.2") } .tag(4) } } } #Preview { ContentView() } and AppView entry point import SwiftUI @main struct RunCoachApp: App { var body: some Scene { WindowGroup { ContentView() } } }
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1
508
Dec ’25
iOS 26 beta5 crash – CALayer position contains NaN when selecting text / showing magnifier / selecting Image's Text in WKWebView
Environment • Device: iOS 26 Developer Beta 5 (23A5308g) • Xcode: 16.3 Short description The app crashes the moment the user tries to long-press to select text inside a WKWebView, double-tap an image with Text (magnifier appears) The exception is CALayer position contains NaN. frame = (nan,0;0,48) chorPoint=(inf, 0) and it is thrown in the UI process. Build & run any project that hosts a WKWebView. Inject the following CSS via script (this is what we do to suppress the native callout menu): WKWebView *webView = [[WKWebView alloc] initWithFrame:self.view.bounds configuration:[WKWebViewConfiguration new]]; NSString *js = @"document.documentElement.style.webkitUserSelect='none';" "document.documentElement.style.webkitTouchCallout='none';"; [webView evaluateJavaScript:js completionHandler:nil]; [self.view addSubview:webView]; Incident Identifier: EE6FB046-5087-4F15-A72D-A74965347A30 CrashReporter Key: 29e8e58e02a07557adb4ce3f463d764f3ce8bbd5 Hardware Model: iPhone16,1 Process: wallet [642] Path: /private/var/containers/Bundle/Application/4B4E609A-C8BF-4C56-AB2A-1638249B98A5/wallet.app/wallet Identifier: xxxx Version: xxxx AppStoreTools: 16F7 AppVariant: 1:iPhone16,1:18 Code Type: ARM-64 (Native) Role: Foreground Parent Process: launchd [1] Coalition: xxxxx Date/Time: 2025-08-06 12:05:24.0732 +0800 Launch Time: 2025-08-06 11:49:40.3802 +0800 OS Version: iPhone OS 26.0 (23A5308g) Release Type: Beta Baseband Version: 3.02.02 Report Version: 104 Exception Type: EXC_CRASH (SIGABRT) Exception Codes: 0x0000000000000000, 0x0000000000000000 Termination Reason: SIGNAL 6 Abort trap: 6 Terminating Process: wallet [642] Triggered by Thread: 0 Application Specific Information: abort() called Last Exception Backtrace: 0 CoreFoundation 0x185e058c8 __exceptionPreprocess + 164 1 libobjc.A.dylib 0x182d797c4 objc_exception_throw + 88 2 CoreFoundation 0x185e908d4 -[NSException initWithCoder:] + 0 3 QuartzCore 0x18678a874 CA::Layer::set_position(CA::Vec2<double> const&, bool) + 160 4 QuartzCore 0x1869a7270 -[CALayer setPosition:] + 52 5 UIKitCore 0x18c4ac564 -[UIView _backing_setPosition:] + 176 6 UIKitCore 0x18cefdf0c -[UIView setCenter:] + 220 7 UIKitCore 0x18cd9f794 -[_UIEditMenuContentPresentation _displayPreparedMenu:titleView:reason:didDismissMenu:configuration:] + 936 8 UIKitCore 0x18cd9f3c0 __54-[_UIEditMenuContentPresentation _displayMenu:reason:]_block_invoke + 104 9 UIKitCore 0x18ced1060 -[UIEditMenuInteraction _editMenuPresentation:preparedMenuForDisplay:completion:] + 384 10 UIKitCore 0x18cd9f2e4 -[_UIEditMenuContentPresentation _displayMenu:reason:] + 304 11 UIKitCore 0x18cd9f0d8 -[_UIEditMenuContentPresentation displayMenu:configuration:] + 64 12 UIKitCore 0x18ced0344 __58-[UIEditMenuInteraction presentEditMenuWithConfiguration:]_block_invoke + 260 13 UIKitCore 0x18ced1f8c __80-[UIEditMenuInteraction _prepareMenuAtLocation:configuration:completionHandler:]_block_invoke + 80 14 UIKitCore 0x18cc8403c __109-[UITextContextMenuInteraction _editMenuInteraction:menuForConfiguration:suggestedActions:completionHandler:]_block_invoke + 180 15 UIKitCore 0x18cc84584 __107-[UITextContextMenuInteraction _querySelectionCommandsForConfiguration:suggestedActions:completionHandler:]_block_invoke + 148 16 WebKit 0x1a05ae5d4 WTF::CompletionHandler<void (WebKit::DocumentEditingContext&&)>::operator()(WebKit::DocumentEditingContext&&) + 64 17 WebKit 0x1a05bb468 WTF::Detail::CallableWrapper<WTF::CompletionHandler<void (IPC::Connection*, IPC::Decoder*)> IPC::Connection::makeAsyncReplyCompletionHandler<Messages::WebPage::RequestDocumentEditingContext, WTF::CompletionHandler<void (WebKit::DocumentEditingContext&&)>>(WTF::CompletionHandler<void (WebKit::DocumentEditingContext&&)>&&, WTF::ThreadLikeAssertion)::'lambda'(IPC::Connection*, IPC::Decoder*), void, IPC::Connection*, IPC::Decoder*>::call(IPC::Connection*, IPC::Decoder*) + 196 18 WebKit 0x19fcf5db8 WTF::Detail::CallableWrapper<WebKit::AuxiliaryProcessProxy::sendMessage(WTF::UniqueRef<IPC::Encoder>&&, WTF::OptionSet<IPC::SendOption>, std::__1::optional<IPC::ConnectionAsyncReplyHandler>, WebKit::AuxiliaryProcessProxy::ShouldStartProcessThrottlerActivity)::$_1, void, IPC::Connection*, IPC::Decoder*>::call(IPC::Connection*, IPC::Decoder*) + 64 19 WebKit 0x19fce54f0 IPC::Connection::dispatchMessage(WTF::UniqueRef<IPC::Decoder>) + 340 20 WebKit 0x19fcf5aa0 IPC::Connection::dispatchIncomingMessages() + 536 21 JavaScriptCore 0x19a8f85d4 WTF::RunLoop::performWork() + 552 22 JavaScriptCore 0x19a8f838c WTF::RunLoop::performWork(void*) + 36 23 CoreFoundation 0x185da6230 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 28 24 CoreFoundation 0x185da61a4 __CFRunLoopDoSource0 + 172 25 CoreFoundation 0x185d83c6c __CFRunLoopDoSources0 + 232 26 CoreFoundation 0x185d598b0 __CFRunLoopRun + 820 27 CoreFoundation 0x185d58c44 _CFRunLoopRunSpecificWithOptions + 532 28 GraphicsServices 0x224ce0498 GSEventRunModal + 120 29 UIKitCore 0x18b6c84b8 -[UIApplication _run] + 792 30 UIKitCore 0x18b66cbc0 UIApplicationMain + 336 31 wallet 0x1046f8558 0x1046f4000 + 17752 32 dyld 0x182dcdb18 start + 6332
5
12
1k
Aug ’25
[iOS 18 Only] Intermittent Crash at completeTransition in Custom Navigation Animation (Firebase Crashlytics)
Hi everyone, I'm encountering an intermittent crash on iOS 18 only (not reproducible locally, reported in Firebase Crashlytics) at transitionContext.completeTransition(!transitionContext.transitionWasCancelled) within my custom UIViewControllerAnimatedTransitioning. The same code runs fine on iOS 16 and 17 (no Crashlytics report for those iOS version) Here's the crash log: Crashed: com.apple.main-thread 0 libswiftCore.dylib 0x4391f0 swift_getObjectType + 40 1 ROOM 0x490c48 ItemDetailAnimator.navigationController(_:animationControllerFor:from:to:) + 47 (ItemDetailAnimator.swift:47) 2 ROOM 0x490f3c @objc ItemDetailAnimator.navigationController(_:animationControllerFor:from:to:) + 92 (<compiler-generated>:92) 3 UIKitCore 0xa2d7a4 -[UINavigationController _customTransitionController:] + 516 4 UIKitCore 0x2e51dc -[UINavigationController _immediatelyApplyViewControllers:transition:animated:operation:] + 2620 5 UIKitCore 0x1541d4 __94-[UINavigationController _applyViewControllers:transition:animated:operation:rescheduleBlock:]_block_invoke + 100 6 UIKitCore 0x150768 -[UINavigationController _applyViewControllers:transition:animated:operation:rescheduleBlock:] + 776 7 UIKitCore 0x2e7e44 -[UINavigationController pushViewController:transition:forceImmediate:] + 544 8 UIKitCore 0x2e4230 -[UINavigationController pushViewController:animated:] + 444 9 ROOM 0x66cb04 UINavigationController.pushViewController(_:animated:completion:) + 185 (UINavigationController+Room.swift:185) 10 ROOM 0x8cef4c ItemDetailCoordinator.start(animated:completion:) + 99 (ItemDetailCoordinator.swift:99) 11 ROOM 0xc6c95c protocol witness for Coordinator.start(animated:completion:) in conformance BaseCoordinator + 24 (<compiler-generated>:24) 12 ROOM 0x8ca520 AppCoordinator.startCoordinator(_:url:reference:animated:completion:) + 729 (AppCoordinator.swift:729) 13 ROOM 0x8cb248 protocol witness for URLSupportCoordinatorOpener.startCoordinator(_:url:reference:animated:completion:) in conformance AppCoordinator + 48 (<compiler-generated>:48) 14 ROOM 0xd6166c URLSupportCoordinatorOpener<>.open(url:openingController:reference:animated:completion:) + 118 (URLSupportedCoordinator.swift:118) 15 ROOM 0xc56038 RRAppDelegate.handleURL(url:completion:) + 588 (RRAppDelegate.swift:588) 16 ROOM 0xc502d0 RRAppDelegate.applicationDidBecomeActive(_:) + 330 (RRAppDelegate.swift:330) 17 ROOM 0xc5041c @objc RRAppDelegate.applicationDidBecomeActive(_:) + 52 (<compiler-generated>:52) 18 UIKitCore 0x1fb048 -[UIApplication _stopDeactivatingForReason:] + 1368 My animateTransition code is: ```func animateTransition( using transitionContext: UIViewControllerContextTransitioning) { guard let (fromView, toView, fromVC, toVC) = filterTargets(context: transitionContext) else { transitionContext.cancelInteractiveTransition() transitionContext.completeTransition(false) return } let containerView = transitionContext.containerView toView.frame = transitionContext.finalFrame(for: toVC) guard let targetView = fromVC.animationTargetView, let fromFrame = fromVC.animationTargetFrame, let toFrame = toVC.animationTargetFrame else { containerView.insertSubview(toView, aboveSubview: fromView) toView.frame = transitionContext.finalFrame(for: toVC) transitionContext.completeTransition(true) return } let newFromFrame = fromView.convert(fromFrame, to: containerView) let tempImageView: UIImageView if let target = targetView as? UIImageView, let image = targetImage ?? target.image, image.size.height != 0, target.frame.height != 0, image.size.width / image.size.height != target.frame.width / target.frame.height { targetImage = image tempImageView = UIImageView(image: image) tempImageView.frame = newFromFrame tempImageView.contentMode = .scaleAspectFit } else { tempImageView = targetView.room.asImageView() tempImageView.frame = newFromFrame } targetView.isHidden = true let tempFromView = containerView.room.asImageView() targetView.isHidden = false let tempHideView = UIView() containerView.addSubview(tempFromView) containerView.insertSubview(toView, aboveSubview: tempFromView) tempHideView.backgroundColor = .white toView.addSubview(tempHideView) containerView.addSubview(tempImageView) //Minus with item detail view y position //Need to minus navigation bar height of item detail view var tempHideViewFrame = toFrame tempHideViewFrame.origin.y -= toView.frame.origin.y tempHideView.frame = tempHideViewFrame let duration = transitionDuration(using: transitionContext) toView.alpha = 0 UIView.animate(withDuration: duration * 0.5, delay: duration * 0.5, options: .curveLinear, animations: { toView.alpha = 1 }) let scale: CGFloat = toFrame.width / newFromFrame.width let newFrame = CGRect( x: toFrame.minX - newFromFrame.minX * scale, y: toFrame.minY - newFromFrame.minY * scale, width: tempFromView.frame.size.width * scale, height: tempFromView.frame.size.height * scale) UIView.animate(withDuration: duration, delay: 0.0, options: [.curveEaseInOut], animations: { tempFromView.frame = newFrame tempImageView.frame = toFrame }, completion: { _ in tempHideView.removeFromSuperview() tempFromView.removeFromSuperview() tempImageView.removeFromSuperview() transitionContext.completeTransition(!transitionContext.transitionWasCancelled) }) }
4
0
243
Apr ’25
"CALayer position contains NaN" Crash in WKWebView on iOS 26 Beta
I’m experiencing a crash in WKWebView on iOS 26 Developer Beta 5 and Beta 6 with the following exception: CALayer position contains NaN: [nan 65] The crash occurs when the following CSS properties are applied to content displayed in WKWebView: -webkit-user-select: none; -webkit-touch-callout: none; This issue happens consistently whenever these styles are set, leading to the crash inside WKWebView. Is this a known bug in the current iOS 26 betas, or is there a recommended workaround?
4
6
599
Aug ’25
Keyframe animation crashes with +[_SwiftUILayerDelegate _screen]: unrecognized selector sent to class on iOS 26
We have an UIViewController called InfoPlayerViewController. Its main subview is from a child view controller backed by SwiftUI via UIHostingController. The InfoPlayerViewController conforms to UIViewControllerTransitioningDelegate. The animation controller for dismissing is DismissPlayerAnimationController. It runs UIKit keyframe animations via UIViewPropertyAnimator. When the keyframe animation is executed there’s an occasional crash for end users in production. It only happens on iOS 26. FB Radar: FB20871547 An example crash is below. Exception Type: EXC_CRASH (SIGABRT) Exception Codes: 0x0000000000000000, 0x0000000000000000 Exception Reason: +[_SwiftUILayerDelegate _screen]: unrecognized selector sent to class 0x20c95da08 Termination Reason: SIGNAL 6 Abort trap: 6 Triggered by Thread: 0 Last Exception Backtrace: 0 CoreFoundation 0x1a23828c8 __exceptionPreprocess + 164 (NSException.m:249) 1 libobjc.A.dylib 0x19f2f97c4 objc_exception_throw + 88 (objc-exception.mm:356) 2 CoreFoundation 0x1a241e6cc +[NSObject(NSObject) doesNotRecognizeSelector:] + 364 (NSObject.m:158) 3 CoreFoundation 0x1a22ff4f8 ___forwarding___ + 1472 (NSForwarding.m:3616) 4 CoreFoundation 0x1a23073a0 _CF_forwarding_prep_0 + 96 (:-1) 5 UIKitCore 0x1a948e880 __35-[UIViewKeyframeAnimationState pop]_block_invoke + 300 (UIView.m:2973) 6 CoreFoundation 0x1a22cb170 __NSDICTIONARY_IS_CALLING_OUT_TO_A_BLOCK__ + 24 (NSDictionaryHelpers.m:10) 7 CoreFoundation 0x1a245d7cc -[__NSDictionaryM enumerateKeysAndObjectsWithOptions:usingBlock:] + 288 (NSDictionaryM.m:271) 8 UIKitCore 0x1a948e6bc -[UIViewKeyframeAnimationState pop] + 376 (UIView.m:2955) 9 UIKitCore 0x1a7bc40e8 +[UIViewAnimationState popAnimationState] + 60 (UIView.m:1250) 10 UIKitCore 0x1a94acc44 +[UIView(UIViewAnimationWithBlocks) _setupAnimationWithDuration:delay:view:options:factory:animations:start:animationStateGenerator:completion:] + 684 (UIView.m:17669) 11 UIKitCore 0x1a94ae334 +[UIView(UIViewKeyframeAnimations) animateKeyframesWithDuration:delay:options:animations:completion:] + 224 (UIView.m:17945) 12 MyApp 0x102c78dec static UIView.animateNestedKeyframe(withRelativeStartTime:relativeDuration:animations:) + 208 (UIView+AnimateNestedKeyframe.swift:10) 13 MyApp 0x102aef3c0 closure #1 in DismissPlayerAnimationController.slideDownBelowTabBarTransitionAnimator(using:) + 156 (DismissPlayerAnimationController.swift:229) 14 MyApp 0x102a2d3d4 <deduplicated_symbol> + 28 15 UIKitCore 0x1a7d5ae5c -[UIViewPropertyAnimator _runAnimations] + 172 (UIViewPropertyAnimator.m:2123) 16 UIKitCore 0x1a83e1594 __49-[UIViewPropertyAnimator startAnimationAsPaused:]_block_invoke_3 + 92 (UIViewPropertyAnimator.m:3557) 17 UIKitCore 0x1a83e1464 __49-[UIViewPropertyAnimator startAnimationAsPaused:]_block_invoke + 96 (UIViewPropertyAnimator.m:3547) 18 UIKitCore 0x1a83e1518 __49-[UIViewPropertyAnimator startAnimationAsPaused:]_block_invoke_2 + 144 (UIViewPropertyAnimator.m:3553) 19 UIKitCore 0x1a83e0e64 -[UIViewPropertyAnimator _setupAnimationTracking:] + 100 (UIViewPropertyAnimator.m:3510) 20 UIKitCore 0x1a83e1264 -[UIViewPropertyAnimator startAnimationAsPaused:] + 728 (UIViewPropertyAnimator.m:3610) 21 UIKitCore 0x1a83de42c -[UIViewPropertyAnimator pauseAnimation] + 68 (UIViewPropertyAnimator.m:2753) 22 UIKitCore 0x1a87d5328 -[UIPercentDrivenInteractiveTransition _startInterruptibleTransition:] + 244 (UIViewControllerTransitioning.m:982) 23 UIKitCore 0x1a87d5514 -[UIPercentDrivenInteractiveTransition startInteractiveTransition:] + 184 (UIViewControllerTransitioning.m:1012) 24 UIKitCore 0x1a7c7931c ___UIViewControllerTransitioningRunCustomTransitionWithRequest_block_invoke_3 + 152 (UIViewControllerTransitioning.m:1579) 25 UIKitCore 0x1a892aefc +[UIKeyboardSceneDelegate _pinInputViewsForKeyboardSceneDelegate:onBehalfOfResponder:duringBlock:] + 96 (UIKeyboardSceneDelegate.m:3518) 26 UIKitCore 0x1a7c79238 ___UIViewControllerTransitioningRunCustomTransitionWithRequest_block_invoke_2 + 236 (UIViewControllerTransitioning.m:1571) 27 UIKitCore 0x1a94ab4b8 +[UIView(Animation) _setAlongsideAnimations:toRunByEndOfBlock:animated:] + 188 (UIView.m:17089) 28 UIKitCore 0x1a7c79070 _UIViewControllerTransitioningRunCustomTransitionWithRequest + 556 (UIViewControllerTransitioning.m:1560) 29 UIKitCore 0x1a86cb7cc __77-[UIPresentationController runTransitionForCurrentStateAnimated:handoffData:]_block_invoke_3 + 1784 (UIPresentationController.m:1504) 30 UIKitCore 0x1a7c43888 -[_UIAfterCACommitBlock run] + 72 (_UIAfterCACommitQueue.m:137) 31 UIKitCore 0x1a7c437c0 -[_UIAfterCACommitQueue flush] + 168 (_UIAfterCACommitQueue.m:228) 32 UIKitCore 0x1a7c436d0 _runAfterCACommitDeferredBlocks + 260 (UIApplication.m:3297) 33 UIKitCore 0x1a7c43c34 _cleanUpAfterCAFlushAndRunDeferredBlocks + 80 (UIApplication.m:3275) 34 UIKitCore 0x1a7c1f104 _UIApplicationFlushCATransaction + 72 (UIApplication.m:3338) 35 UIKitCore 0x1a7c1f024 __setupUpdateSequence_block_invoke_2 + 352 (_UIUpdateScheduler.m:1634) 36 UIKitCore 0x1a7c2cee8 _UIUpdateSequenceRunNext + 128 (_UIUpdateSequence.mm:189) 37 UIKitCore 0x1a7c2c378 schedulerStepScheduledMainSectionContinue + 60 (_UIUpdateScheduler.m:1185) 38 UpdateCycle 0x28c58f5f8 UC::DriverCore::continueProcessing() + 84 (UCDriver.cc:288) 39 CoreFoundation 0x1a2323230 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 28 (CFRunLoop.c:2021) 40 CoreFoundation 0x1a23231a4 __CFRunLoopDoSource0 + 172 (CFRunLoop.c:2065) 41 CoreFoundation 0x1a2300c6c __CFRunLoopDoSources0 + 232 (CFRunLoop.c:2102) 42 CoreFoundation 0x1a22d68b0 __CFRunLoopRun + 820 (CFRunLoop.c:2983) 43 CoreFoundation 0x1a22d5c44 _CFRunLoopRunSpecificWithOptions + 532 (CFRunLoop.c:3462) 44 GraphicsServices 0x2416a2498 GSEventRunModal + 120 (GSEvent.c:2049) 45 UIKitCore 0x1a7c50ddc -[UIApplication _run] + 792 (UIApplication.m:3899) 46 UIKitCore 0x1a7bf5b0c UIApplicationMain + 336 (UIApplication.m:5574) // ...
4
1
623
Jan ’26
CATiledLayer flashes and re-draws entirely when re-drawing a single tile
I have filed a bug report for this (FB17734946), but I'm posting it here verbatim in case others have the same issue and in hopes of getting attention from an Apple engineer sooner. When calling setNeedsDisplayInRect on a CATiledLayer - or a UIView whose backing layer is CATiledLayer - one would expect to re-draw only a region identified by the rect passed to the method. This is even written in the documentation for the class: "Regions of the layer may be invalidated using the setNeedsDisplayInRect: method however the update will be asynchronous. While the next display update will most likely not contain the updated content, a future update will." However, upon calling this method, CATiledLayer redraws whole contents instead of just the tile at the specified rect, and it flashes when doing so. It behaves exactly the same as if one had called setNeedsDisplay without passing any rect; all contents are cleared and re-drawn again. I'm 100% sure I've passed in the correct rect of the exact tile that I need to redraw. I have even tried passing much smaller rects, but still the same. (And yes, the rect I've passed accounts for the current level of detail.) I have found this GitHub repo https://github.com/frankus/NetPhotoScroller, which based on discussion from here https://forums.macrumors.com/threads/catiledlayer-blanks-out-tiles-when-redrawing.1333948/ aims at solving these issues by using two private methods on CATiledLayer class: (void)setNeedsDisplayInRect:(CGRect)r levelOfDetail:(int)level; (BOOL)canDrawRect:(CGRect)rect levelOfDetail:(int)level; I have explored the repo in detail, however I wasn't able to test exactly this code from the GitHub repo. I have tried using those two private methods myself (through an Objective-C class that defines the methods in the header file and then a swift class which inherits it), but I couldn't solve the issue; the flashing and the full re-draw is still there. After doing a lot of research, the conclusion seems to be that one cannot use CATiledLayer with contents that are downloaded remotely, on demand, as tiles are being requested. I have, however, found one interesting thing which seems to work so far: before calling setNeedsDisplayInRect (or just setNeedsDisplay, as they behave the same for CATiledLayer in my testing), cache the current layer's contents, and after calling setNeedsDisplay (or setNeedsDisplayInRect), restore the contents back to the layer. This prevents flashing and preserves any tiles that were drawn at the time of the re-draw. let c = tiledLayer.contents tiledLayer.setNeedsDisplay(tileRect) tiledLayer.contents = c However! Docs clearly state the warning: Do not attempt to directly modify the contents property of a CATiledLayer object. Doing so disables the ability of a tiled layer to asynchronously provide tiled content, effectively turning the layer into a regular CALayer object. I believe this message implies modifying the contents property with some raw content, like image data, and that it may be safe to re-apply the existing contents (which are in my testing of type CAImageProvider) -- but I can't rely on an implementation detail in my production app. I have tested this and confirmed that the bug appears on: iPhone 14 Pro, iOS 18.5 iPhone 13 Pro, iOS 17.5.1 iPhone 5s, iOS 15.8.3 iPad Pro 1st gen, iPadOS 18.4.1 a couple simulator versions I can also confirm that the fix (to re-apply contents property) is also working properly on all these versions. Is this expected behavior, that tiled layer redraws itself entirely instead of redrawing specific tiles? Is it safe to modify contents of a CATiledLayer by re-applying the existing contents? If not, is there an alternative to avoid flashing?
3
0
204
May ’25
Why does CADisplayLink of an external UIScreen drift in time?
I am using Apple's original Lightning Digital AV-adapter (Lightning-to-HDMI dongle) to connect my iPhone to an external display via a HDMI cable. I need to synchronize rendering with the external display's refresh rate, so I create a new CADisplayLink tied to the external display's UIScreen: UIScreen.screens[externalDisplayIdx].displayLink(withTarget:, selector:). The callback is being called regularly, but with increasing delay relative to the CADisplayLink.timestamp, so the next time the callback is called, I have less and less time to draw the next frame (see the snippet below). Assuming 60 FPS, the value of secondsTillDeadline starts at an arbitrary value in the range of approx -0.0001 to 0.0166667, and then it slowly decreases towards zero (and for a brief period it goes into small negative numbers). Once it reaches zero, it flips back to 0.0166667 and continues to decrease again. This cycle repeats indefinitely. Changing the external display's resolution (UIScreen's mode) or the CADisplayLink's preferredFrameRateRange to a lower FPS does not seem to have any effect on the temporal drifting (even the rate of change seem to be the same). When I create a new CADisplayLink for the iPhone's main screen, the value of secondsTillDeadline is stable, it does not drift and it is very close to 0.0166667, as expected. Is this drift caused by the external monitor or by Apple's Lightning-to-HDMI dongle ...or is the problem somewhere else? Can the drifting be stopped? func onDisplayLinkUpdate(displayLink: CADisplayLink) { // Gradually decreases from 0.01667 to -0.0001, then flips back to 0.01667 and continues to decrease let secondsTillDeadline = displayLink.targetTimestamp - CACurrentMediaTime() }
3
0
472
Aug ’25
Core Text incremental redraw glitch: overlapping glyphs during editing
During editing in Pages (or Word) I am getting these glitches (see attachment). Started after the last update to Mac OS 26.3 (beta) Also removed 2 recent instalments (Blackhole audio driver and kDrive/Infomaniak, but trouble is still there. 27" iMac 2020 (Intel) i7 3,8 Ghz AMD Radeon Pro 5500 XT 8 GB 24 GB RAM macOS Tahoe 26.3 (=beta) Tried restart in safe mode, checked fonts. Talked to aissistent to get a solution, but no ...) Thx for any advice, Pieter (not a developer so please kee pit simple 🙏🏻)
3
0
544
Feb ’26
SwiftUI Transaction completion handler is being called unexpectedly
Unexpected SwiftUI Transaction Behavior This minimal example demonstrates an unexpected behavior in SwiftUI's Transaction API: var transaction = Transaction(animation: .none) transaction.addAnimationCompletion { print("This should not be called!") } The Issue The completion handler is called immediately after creation, even though the transaction was never used in any SwiftUI animation context (like withTransaction or other animation-related APIs). Expected vs Actual Behavior Expected: The completion handler should only be called after the transaction is actually used in a SwiftUI animation. Actual: The completion handler is called right after creation, regardless of whether the transaction is used or not. Current Workaround To avoid this, I'm forced to implement defensive programming: only creating transactions with completion handlers at the exact moment they're going to be used. This adds unnecessary complexity and goes against the intuitive usage of the Transactions API.
2
0
138
Jun ’25
Animation Ghosting with animation-timeline on 120HZ ProMotion Devices
On iOS Devices with ProMotion (120HZ) if you animate Elements on your Page with animation-timeline you get Ghosting Effects. You can not see the Ghosting with a Simulator or on Screenshots, only on real Devices. To Reproduce I made a Minimal Example: https://codesandbox.io/p/sandbox/120hztest-xrwgtc When you scroll quickly on the Page with an iOS 120HZ Device (https://en.wikipedia.org/wiki/List_of_smartphones_with_a_high_refresh_rate_display) you will see ghosting on the Top of the right Element (animation-timeline) and no ghosting on the other animated Element. (I edited the Screenshot, to Illustrate how the Effect looks like, since it is only visible on the real Display)
2
0
248
Jan ’26
Animation Help
Hello, I am trying to use matchedGeometryEffect to animate between an item in a list view and the item's detail view. Right now, I am getting an unwanted cross-fade animation as the view transitions. So the list item moves into place as it should with the modifier, but it fades out as its detail version fades in, which I do not want. I do not want any fading at all, just the movement from one component to the other. How do I stop this? Thanks.
2
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81
Jan ’26
Navigation Bar animation upon Tab change
Hi. Since Xcode 16 and/or iOS 18.0 (I upgraded at the same time), I have an strange effect in the lower (let's say) 20% section of the Navigation Bar when changing to another tab, and this independently if large titles are used or not. Mentioned section is brighter or darker than the rest of the Navigation Bar background, depending on which background tint is used. This effect lasts about 0.3 seconds, but is clearly visible, quite disturbing and new as of Xcode 16 and/or iOS 18.0. I use the code below in AppDelegate to get a gradient coloured Navigation Bar background. let appearance = UINavigationBarAppearance() UINavigationBar.appearance().standardAppearance = appearance UINavigationBar.appearance().compactAppearance = appearance UINavigationBar.appearance().scrollEdgeAppearance = appearance UINavigationBar.appearance().compactScrollEdgeAppearance = appearance If I don't use above code., the background color is filled and without gradient. Subject effect doesn't show in this case. The effect basically looks like when changing tab, the new Navigation Bar background doesn't clear right away, and keeps the background from the previous Navigation Bar for 0.3 seconds before new one Navigation Bar background is rendered. I spent quite some time on changing every possible setting, in code as well as storyboard ... no success so far. Any ideas how to disable this undesired animation?
1
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790
Oct ’25
UI freeze during layouting
One of our users reported a very strange bug where our app freezes and eventually crashes on some screen transitions. From different crash logs we could determine that the app freezes up when we call view.layoutIfNeeded() for animating constraint changes. It then gets killed by the watchdog 10 seconds later: Exception Type: EXC_CRASH (SIGKILL) Exception Codes: 0x0000000000000000, 0x0000000000000000 Termination Reason: FRONTBOARD 2343432205 <RBSTerminateContext| domain:10 code:0x8BADF00D explanation:scene-update watchdog transgression: app<bundleID(2A01F261-3554-44C0-B5A9-EBEB446484AD)>:6921 exhausted real (wall clock) time allowance of 10.00 seconds ProcessVisibility: Background ProcessState: Running WatchdogEvent: scene-update WatchdogVisibility: Background WatchdogCPUStatistics: ( "Elapsed total CPU time (seconds): 24.320 (user 18.860, system 5.460), 29% CPU", "Elapsed application CPU time (seconds): 10.630, 12% CPU" ) reportType:CrashLog maxTerminationResistance:Interactive> The crash stack trace looks slightly different, depending on the UI transition that is happening. Here are the two we observed so far. Both are triggered by the layoutIfNeeded() call. Thread 0 name: Dispatch queue: com.apple.main-thread Thread 0 Crashed: 0 CoreAutoLayout 0x1b09f90e4 -[NSISEngine valueForEngineVar:] + 8 1 UIKitCore 0x18f919478 -[_UIViewLayoutEngineRelativeAlignmentRectOriginCache origin] + 372 2 UIKitCore 0x18f918f18 -[UIView _nsis_center:bounds:inEngine:forLayoutGuide:] + 1372 3 UIKitCore 0x18f908e9c -[UIView(Geometry) _applyISEngineLayoutValuesToBoundsOnly:] + 248 4 UIKitCore 0x18f9089e0 -[UIView(Geometry) _resizeWithOldSuperviewSize:] + 148 5 CoreFoundation 0x18d0cd6a4 __NSARRAY_IS_CALLING_OUT_TO_A_BLOCK__ + 24 6 CoreFoundation 0x18d0cd584 -[__NSArrayM enumerateObjectsWithOptions:usingBlock:] + 432 7 UIKitCore 0x18f8e62b0 -[UIView(Geometry) resizeSubviewsWithOldSize:] + 128 8 UIKitCore 0x18f977194 -[UIView(AdditionalLayoutSupport) _is_layout] + 124 9 UIKitCore 0x18f976c2c -[UIView _updateConstraintsAsNecessaryAndApplyLayoutFromEngine] + 800 10 UIKitCore 0x18f903944 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 2728 11 QuartzCore 0x18ec15498 CA::Layer::layout_if_needed(CA::Transaction*) + 496 12 UIKitCore 0x18f940c10 -[UIView(Hierarchy) layoutBelowIfNeeded] + 312 Thread 0 name: Dispatch queue: com.apple.main-thread Thread 0 Crashed: 0 QuartzCore 0x18ec2cfe0 -[CALayer animationForKey:] + 176 1 UIKitCore 0x18fa5b258 UniqueAnimationKeyForLayer + 192 2 UIKitCore 0x18fa5ab7c __67-[_UIViewAdditiveAnimationAction runActionForKey:object:arguments:]_block_invoke_2 + 468 3 UIKitCore 0x18fa5ba5c -[_UIViewAdditiveAnimationAction runActionForKey:object:arguments:] + 1968 4 QuartzCore 0x18eb9e938 CA::Layer::set_bounds(CA::Rect const&, bool) + 428 5 QuartzCore 0x18eb9e760 -[CALayer setBounds:] + 132 6 UIKitCore 0x18f941770 -[UIView _backing_setBounds:] + 64 7 UIKitCore 0x18f940404 -[UIView(Geometry) setBounds:] + 340 8 UIKitCore 0x18f908f84 -[UIView(Geometry) _applyISEngineLayoutValuesToBoundsOnly:] + 480 9 UIKitCore 0x18f9089e0 -[UIView(Geometry) _resizeWithOldSuperviewSize:] + 148 10 CoreFoundation 0x18d0cd6a4 __NSARRAY_IS_CALLING_OUT_TO_A_BLOCK__ + 24 11 CoreFoundation 0x18d132488 -[__NSSingleObjectArrayI enumerateObjectsWithOptions:usingBlock:] + 92 12 UIKitCore 0x18f8e62b0 -[UIView(Geometry) resizeSubviewsWithOldSize:] + 128 13 UIKitCore 0x18f977194 -[UIView(AdditionalLayoutSupport) _is_layout] + 124 14 UIKitCore 0x18f976c2c -[UIView _updateConstraintsAsNecessaryAndApplyLayoutFromEngine] + 800 15 UIKitCore 0x18f916258 -[UIView(Hierarchy) layoutSubviews] + 204 16 UIKitCore 0x18f903814 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 2424 17 QuartzCore 0x18ec15498 CA::Layer::layout_if_needed(CA::Transaction*) + 496 18 UIKitCore 0x18f940c10 -[UIView(Hierarchy) layoutBelowIfNeeded] + 312 So far, we only know of one iPad Air M1 where this is happening. But we don't know how many users experience this issue without reporting it. Does anyone know what could cause Auto Layout or Core Animation to block in those calls? We have no clue so far...
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210
Apr ’25
How to obtain frame rate for iOS proMotion devices
Due to the release of ProMotion devices, the system may switch frame rates in certain scenarios, resulting in the loss of reference value for data collected through CADisplayLink callbacks at a fixed 60Hz frame rate. We cannot distinguish whether the slow callback of CADisplayLink is due to a stutter or a system switch in frame rate. I know Hitch Time Ratio, but I can't use this scheme for some reasons. How can I distinguish between stuck and frame rate gear shift in CADisplaylink callback? In iOS 15, CADisplayLink.preferredFrameRateRange.preferred always returns 0, while minimum and maximum do change. Can I use these minimum and maximum range values as criteria to distinguish between frame rate switching and stuttering?
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162
May ’25
STextField becomes blurry after layer transform on macOS 26 (Tahoe)
Hi everyone, After upgrading to macOS 26 (Tahoe) I’ve run into an issue: NSTextField becomes noticeably blurry when its parent layer is transformed (CATransform3D or CGAffineTransform). On macOS 15 (Sequoia) the exact same code worked fine — text stayed sharp. Interestingly, an NSImage backed by a PDF representation transforms without any problem and remains perfectly crisp, but labels do not. What I’ve tried so far Checked the contentsScale of the layers Setting magnificationFilter = .nearest Toggled shouldRasterize on/off and adjusted rasterizationScale Have there been any Core Animation or AppKit changes in macOS 26 that affect text rendering when transforming layers? What’s the recommended way now to keep NSTextField text sharp (similar to how vector PDF images behave) when scaling its parent layer? Any insights, best practices, or workarounds would be greatly appreciated. Thanks in advance!
1
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216
Sep ’25
iOS 26 Beta breaks scroll/gesture in SwiftUI chat (worked in iOS 18): Simultaneous gestures & ScrollViewReader issues
Hi all, After upgrading to the iOS 26 beta, the scrolling in my SwiftUI chat view is completely broken. The exact same code works perfectly on iOS 18. Context: I have a chat view using ScrollViewReader and a vertically-reversed ScrollView (with .rotationEffect(.degrees(180))). Each message row (MessageBubble) uses multiple simultaneousGesture handlers: Horizontal drag for swipe-to-reply (and other actions: pin, delete) Long press for showing popover/actions Vertical scroll for normal chat scrolling This was working great on iOS 18. In iOS 26 beta, the vertical scroll is either completely disabled, jittery, or hijacked by the message row’s drag gestures, even though .simultaneousGesture is used (see code below). Minimal Repro Sample MessageListView.swift swift Copy Edit ScrollViewReader { proxy in ScrollView(.vertical, showsIndicators: false) { LazyVStack(spacing: 0) { // ... grouped messages ForEach(...) { ... MessageBubble(...) // see below } Color.clear.frame(height: 8).id("BOTTOM_ANCHOR") } .padding(.horizontal, 4) .rotationEffect(.degrees(180)) } .rotationEffect(.degrees(180)) } MessageBubble.swift struct MessageBubble: View { // ... var body: some View { // horizontal swipe-to-reply gesture let dragGesture = DragGesture(minimumDistance: 10) // ... ZStack { // ... HStack { ... } // ... .simultaneousGesture( DragGesture(minimumDistance: 0) // for long press // ... ) .simultaneousGesture(dragGesture) // for horizontal swipe } // ... } }
Replies
8
Boosts
10
Views
1.3k
Activity
Sep ’25
My app doesn't respond on iPhone Air iOS 26.1.
My app doesn't respond on iPhone Air iOS 26.1. After startup, my app shows the main view with a tab bar controller containing 4 navigation controllers. However, when a second-level view controller is pushed onto any navigation controller, the UI freezes and becomes unresponsive. The iPhone simulator running iOS 26.1 exhibits the same problem. The debug profile shows CPU usage at 100%. However, other devices and simulators do not have this problem.
Replies
7
Boosts
3
Views
539
Activity
3d
Incorrect transitionFlipFromRight animations on iOS 26.1
On devices and simulators with iOS 26.1, the animation does not work correctly (the initial and final screens are distorted). I use open class func transition(with view: UIView, duration: TimeInterval, options: UIView.AnimationOptions = [], animations: (() -> Void)?, completion: ((Bool) -> Void)? = nil) with options: .transitionFlipFromRight
Replies
6
Boosts
3
Views
299
Activity
Nov ’25
Liquid Glass TabBar animations causes Hangs, bug with UIKitCore?
With iOS 26.1 we started seeing a bug that only appears on iPhone Air. This bug is visible with simulators too. I have tried so many different ways to fix the issue, but Instruments Profiler is pointing at UIKitCore. We load a tab bar, when the user attempts to switch a tab, the app hangs and never recovers. It happens right as the animation of the Glass bubble is in progress. I have tried a UIKit Tab bar, a SwiftUI Tab bar. I tore out AppDelegate and did a direct @main SwiftUI entry for my application. This issue appears with every tab bar instance I try. I attempted to disable LiquidGlass by utilizing this flag UIDesignRequiresCompatibility in my plist, but the flag seems to be ignored by the system. I am not sure what else to try. I have a trace file if that is helpful. What else can I upload? Here is what the code looks like. struct ContentView: View { @State private var selectedTab = 2 var body: some View { TabView(selection: $selectedTab) { Text("Profile") .tabItem { Label("Me", systemImage: "person") } .tag(0) Text("Training") .tabItem { Label("Training", systemImage: "calendar") } .tag(1) Text("Home") .tabItem { Label("Home", systemImage: "house") } .tag(2) Text("Goals") .tabItem { Label("Goals", systemImage: "target") } .tag(3) Text("Coach") .tabItem { Label("Coach", systemImage: "person.2") } .tag(4) } } } #Preview { ContentView() } and AppView entry point import SwiftUI @main struct RunCoachApp: App { var body: some Scene { WindowGroup { ContentView() } } }
Replies
6
Boosts
1
Views
508
Activity
Dec ’25
iOS 26 beta5 crash – CALayer position contains NaN when selecting text / showing magnifier / selecting Image's Text in WKWebView
Environment • Device: iOS 26 Developer Beta 5 (23A5308g) • Xcode: 16.3 Short description The app crashes the moment the user tries to long-press to select text inside a WKWebView, double-tap an image with Text (magnifier appears) The exception is CALayer position contains NaN. frame = (nan,0;0,48) chorPoint=(inf, 0) and it is thrown in the UI process. Build &amp; run any project that hosts a WKWebView. Inject the following CSS via script (this is what we do to suppress the native callout menu): WKWebView *webView = [[WKWebView alloc] initWithFrame:self.view.bounds configuration:[WKWebViewConfiguration new]]; NSString *js = @"document.documentElement.style.webkitUserSelect='none';" "document.documentElement.style.webkitTouchCallout='none';"; [webView evaluateJavaScript:js completionHandler:nil]; [self.view addSubview:webView]; Incident Identifier: EE6FB046-5087-4F15-A72D-A74965347A30 CrashReporter Key: 29e8e58e02a07557adb4ce3f463d764f3ce8bbd5 Hardware Model: iPhone16,1 Process: wallet [642] Path: /private/var/containers/Bundle/Application/4B4E609A-C8BF-4C56-AB2A-1638249B98A5/wallet.app/wallet Identifier: xxxx Version: xxxx AppStoreTools: 16F7 AppVariant: 1:iPhone16,1:18 Code Type: ARM-64 (Native) Role: Foreground Parent Process: launchd [1] Coalition: xxxxx Date/Time: 2025-08-06 12:05:24.0732 +0800 Launch Time: 2025-08-06 11:49:40.3802 +0800 OS Version: iPhone OS 26.0 (23A5308g) Release Type: Beta Baseband Version: 3.02.02 Report Version: 104 Exception Type: EXC_CRASH (SIGABRT) Exception Codes: 0x0000000000000000, 0x0000000000000000 Termination Reason: SIGNAL 6 Abort trap: 6 Terminating Process: wallet [642] Triggered by Thread: 0 Application Specific Information: abort() called Last Exception Backtrace: 0 CoreFoundation 0x185e058c8 __exceptionPreprocess + 164 1 libobjc.A.dylib 0x182d797c4 objc_exception_throw + 88 2 CoreFoundation 0x185e908d4 -[NSException initWithCoder:] + 0 3 QuartzCore 0x18678a874 CA::Layer::set_position(CA::Vec2&lt;double&gt; const&amp;, bool) + 160 4 QuartzCore 0x1869a7270 -[CALayer setPosition:] + 52 5 UIKitCore 0x18c4ac564 -[UIView _backing_setPosition:] + 176 6 UIKitCore 0x18cefdf0c -[UIView setCenter:] + 220 7 UIKitCore 0x18cd9f794 -[_UIEditMenuContentPresentation _displayPreparedMenu:titleView:reason:didDismissMenu:configuration:] + 936 8 UIKitCore 0x18cd9f3c0 __54-[_UIEditMenuContentPresentation _displayMenu:reason:]_block_invoke + 104 9 UIKitCore 0x18ced1060 -[UIEditMenuInteraction _editMenuPresentation:preparedMenuForDisplay:completion:] + 384 10 UIKitCore 0x18cd9f2e4 -[_UIEditMenuContentPresentation _displayMenu:reason:] + 304 11 UIKitCore 0x18cd9f0d8 -[_UIEditMenuContentPresentation displayMenu:configuration:] + 64 12 UIKitCore 0x18ced0344 __58-[UIEditMenuInteraction presentEditMenuWithConfiguration:]_block_invoke + 260 13 UIKitCore 0x18ced1f8c __80-[UIEditMenuInteraction _prepareMenuAtLocation:configuration:completionHandler:]_block_invoke + 80 14 UIKitCore 0x18cc8403c __109-[UITextContextMenuInteraction _editMenuInteraction:menuForConfiguration:suggestedActions:completionHandler:]_block_invoke + 180 15 UIKitCore 0x18cc84584 __107-[UITextContextMenuInteraction _querySelectionCommandsForConfiguration:suggestedActions:completionHandler:]_block_invoke + 148 16 WebKit 0x1a05ae5d4 WTF::CompletionHandler&lt;void (WebKit::DocumentEditingContext&amp;&amp;)&gt;::operator()(WebKit::DocumentEditingContext&amp;&amp;) + 64 17 WebKit 0x1a05bb468 WTF::Detail::CallableWrapper&lt;WTF::CompletionHandler&lt;void (IPC::Connection*, IPC::Decoder*)&gt; IPC::Connection::makeAsyncReplyCompletionHandler&lt;Messages::WebPage::RequestDocumentEditingContext, WTF::CompletionHandler&lt;void (WebKit::DocumentEditingContext&amp;&amp;)&gt;&gt;(WTF::CompletionHandler&lt;void (WebKit::DocumentEditingContext&amp;&amp;)&gt;&amp;&amp;, WTF::ThreadLikeAssertion)::'lambda'(IPC::Connection*, IPC::Decoder*), void, IPC::Connection*, IPC::Decoder*&gt;::call(IPC::Connection*, IPC::Decoder*) + 196 18 WebKit 0x19fcf5db8 WTF::Detail::CallableWrapper&lt;WebKit::AuxiliaryProcessProxy::sendMessage(WTF::UniqueRef&lt;IPC::Encoder&gt;&amp;&amp;, WTF::OptionSet&lt;IPC::SendOption&gt;, std::__1::optional&lt;IPC::ConnectionAsyncReplyHandler&gt;, WebKit::AuxiliaryProcessProxy::ShouldStartProcessThrottlerActivity)::$_1, void, IPC::Connection*, IPC::Decoder*&gt;::call(IPC::Connection*, IPC::Decoder*) + 64 19 WebKit 0x19fce54f0 IPC::Connection::dispatchMessage(WTF::UniqueRef&lt;IPC::Decoder&gt;) + 340 20 WebKit 0x19fcf5aa0 IPC::Connection::dispatchIncomingMessages() + 536 21 JavaScriptCore 0x19a8f85d4 WTF::RunLoop::performWork() + 552 22 JavaScriptCore 0x19a8f838c WTF::RunLoop::performWork(void*) + 36 23 CoreFoundation 0x185da6230 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 28 24 CoreFoundation 0x185da61a4 __CFRunLoopDoSource0 + 172 25 CoreFoundation 0x185d83c6c __CFRunLoopDoSources0 + 232 26 CoreFoundation 0x185d598b0 __CFRunLoopRun + 820 27 CoreFoundation 0x185d58c44 _CFRunLoopRunSpecificWithOptions + 532 28 GraphicsServices 0x224ce0498 GSEventRunModal + 120 29 UIKitCore 0x18b6c84b8 -[UIApplication _run] + 792 30 UIKitCore 0x18b66cbc0 UIApplicationMain + 336 31 wallet 0x1046f8558 0x1046f4000 + 17752 32 dyld 0x182dcdb18 start + 6332
Replies
5
Boosts
12
Views
1k
Activity
Aug ’25
[iOS 18 Only] Intermittent Crash at completeTransition in Custom Navigation Animation (Firebase Crashlytics)
Hi everyone, I'm encountering an intermittent crash on iOS 18 only (not reproducible locally, reported in Firebase Crashlytics) at transitionContext.completeTransition(!transitionContext.transitionWasCancelled) within my custom UIViewControllerAnimatedTransitioning. The same code runs fine on iOS 16 and 17 (no Crashlytics report for those iOS version) Here's the crash log: Crashed: com.apple.main-thread 0 libswiftCore.dylib 0x4391f0 swift_getObjectType + 40 1 ROOM 0x490c48 ItemDetailAnimator.navigationController(_:animationControllerFor:from:to:) + 47 (ItemDetailAnimator.swift:47) 2 ROOM 0x490f3c @objc ItemDetailAnimator.navigationController(_:animationControllerFor:from:to:) + 92 (<compiler-generated>:92) 3 UIKitCore 0xa2d7a4 -[UINavigationController _customTransitionController:] + 516 4 UIKitCore 0x2e51dc -[UINavigationController _immediatelyApplyViewControllers:transition:animated:operation:] + 2620 5 UIKitCore 0x1541d4 __94-[UINavigationController _applyViewControllers:transition:animated:operation:rescheduleBlock:]_block_invoke + 100 6 UIKitCore 0x150768 -[UINavigationController _applyViewControllers:transition:animated:operation:rescheduleBlock:] + 776 7 UIKitCore 0x2e7e44 -[UINavigationController pushViewController:transition:forceImmediate:] + 544 8 UIKitCore 0x2e4230 -[UINavigationController pushViewController:animated:] + 444 9 ROOM 0x66cb04 UINavigationController.pushViewController(_:animated:completion:) + 185 (UINavigationController+Room.swift:185) 10 ROOM 0x8cef4c ItemDetailCoordinator.start(animated:completion:) + 99 (ItemDetailCoordinator.swift:99) 11 ROOM 0xc6c95c protocol witness for Coordinator.start(animated:completion:) in conformance BaseCoordinator + 24 (<compiler-generated>:24) 12 ROOM 0x8ca520 AppCoordinator.startCoordinator(_:url:reference:animated:completion:) + 729 (AppCoordinator.swift:729) 13 ROOM 0x8cb248 protocol witness for URLSupportCoordinatorOpener.startCoordinator(_:url:reference:animated:completion:) in conformance AppCoordinator + 48 (<compiler-generated>:48) 14 ROOM 0xd6166c URLSupportCoordinatorOpener<>.open(url:openingController:reference:animated:completion:) + 118 (URLSupportedCoordinator.swift:118) 15 ROOM 0xc56038 RRAppDelegate.handleURL(url:completion:) + 588 (RRAppDelegate.swift:588) 16 ROOM 0xc502d0 RRAppDelegate.applicationDidBecomeActive(_:) + 330 (RRAppDelegate.swift:330) 17 ROOM 0xc5041c @objc RRAppDelegate.applicationDidBecomeActive(_:) + 52 (<compiler-generated>:52) 18 UIKitCore 0x1fb048 -[UIApplication _stopDeactivatingForReason:] + 1368 My animateTransition code is: ```func animateTransition( using transitionContext: UIViewControllerContextTransitioning) { guard let (fromView, toView, fromVC, toVC) = filterTargets(context: transitionContext) else { transitionContext.cancelInteractiveTransition() transitionContext.completeTransition(false) return } let containerView = transitionContext.containerView toView.frame = transitionContext.finalFrame(for: toVC) guard let targetView = fromVC.animationTargetView, let fromFrame = fromVC.animationTargetFrame, let toFrame = toVC.animationTargetFrame else { containerView.insertSubview(toView, aboveSubview: fromView) toView.frame = transitionContext.finalFrame(for: toVC) transitionContext.completeTransition(true) return } let newFromFrame = fromView.convert(fromFrame, to: containerView) let tempImageView: UIImageView if let target = targetView as? UIImageView, let image = targetImage ?? target.image, image.size.height != 0, target.frame.height != 0, image.size.width / image.size.height != target.frame.width / target.frame.height { targetImage = image tempImageView = UIImageView(image: image) tempImageView.frame = newFromFrame tempImageView.contentMode = .scaleAspectFit } else { tempImageView = targetView.room.asImageView() tempImageView.frame = newFromFrame } targetView.isHidden = true let tempFromView = containerView.room.asImageView() targetView.isHidden = false let tempHideView = UIView() containerView.addSubview(tempFromView) containerView.insertSubview(toView, aboveSubview: tempFromView) tempHideView.backgroundColor = .white toView.addSubview(tempHideView) containerView.addSubview(tempImageView) //Minus with item detail view y position //Need to minus navigation bar height of item detail view var tempHideViewFrame = toFrame tempHideViewFrame.origin.y -= toView.frame.origin.y tempHideView.frame = tempHideViewFrame let duration = transitionDuration(using: transitionContext) toView.alpha = 0 UIView.animate(withDuration: duration * 0.5, delay: duration * 0.5, options: .curveLinear, animations: { toView.alpha = 1 }) let scale: CGFloat = toFrame.width / newFromFrame.width let newFrame = CGRect( x: toFrame.minX - newFromFrame.minX * scale, y: toFrame.minY - newFromFrame.minY * scale, width: tempFromView.frame.size.width * scale, height: tempFromView.frame.size.height * scale) UIView.animate(withDuration: duration, delay: 0.0, options: [.curveEaseInOut], animations: { tempFromView.frame = newFrame tempImageView.frame = toFrame }, completion: { _ in tempHideView.removeFromSuperview() tempFromView.removeFromSuperview() tempImageView.removeFromSuperview() transitionContext.completeTransition(!transitionContext.transitionWasCancelled) }) }
Replies
4
Boosts
0
Views
243
Activity
Apr ’25
ios 26, CAShapeLayer with pattern image not work
please fix!
Replies
4
Boosts
2
Views
397
Activity
Oct ’25
"CALayer position contains NaN" Crash in WKWebView on iOS 26 Beta
I’m experiencing a crash in WKWebView on iOS 26 Developer Beta 5 and Beta 6 with the following exception: CALayer position contains NaN: [nan 65] The crash occurs when the following CSS properties are applied to content displayed in WKWebView: -webkit-user-select: none; -webkit-touch-callout: none; This issue happens consistently whenever these styles are set, leading to the crash inside WKWebView. Is this a known bug in the current iOS 26 betas, or is there a recommended workaround?
Replies
4
Boosts
6
Views
599
Activity
Aug ’25
Keyframe animation crashes with +[_SwiftUILayerDelegate _screen]: unrecognized selector sent to class on iOS 26
We have an UIViewController called InfoPlayerViewController. Its main subview is from a child view controller backed by SwiftUI via UIHostingController. The InfoPlayerViewController conforms to UIViewControllerTransitioningDelegate. The animation controller for dismissing is DismissPlayerAnimationController. It runs UIKit keyframe animations via UIViewPropertyAnimator. When the keyframe animation is executed there’s an occasional crash for end users in production. It only happens on iOS 26. FB Radar: FB20871547 An example crash is below. Exception Type: EXC_CRASH (SIGABRT) Exception Codes: 0x0000000000000000, 0x0000000000000000 Exception Reason: +[_SwiftUILayerDelegate _screen]: unrecognized selector sent to class 0x20c95da08 Termination Reason: SIGNAL 6 Abort trap: 6 Triggered by Thread: 0 Last Exception Backtrace: 0 CoreFoundation 0x1a23828c8 __exceptionPreprocess + 164 (NSException.m:249) 1 libobjc.A.dylib 0x19f2f97c4 objc_exception_throw + 88 (objc-exception.mm:356) 2 CoreFoundation 0x1a241e6cc +[NSObject(NSObject) doesNotRecognizeSelector:] + 364 (NSObject.m:158) 3 CoreFoundation 0x1a22ff4f8 ___forwarding___ + 1472 (NSForwarding.m:3616) 4 CoreFoundation 0x1a23073a0 _CF_forwarding_prep_0 + 96 (:-1) 5 UIKitCore 0x1a948e880 __35-[UIViewKeyframeAnimationState pop]_block_invoke + 300 (UIView.m:2973) 6 CoreFoundation 0x1a22cb170 __NSDICTIONARY_IS_CALLING_OUT_TO_A_BLOCK__ + 24 (NSDictionaryHelpers.m:10) 7 CoreFoundation 0x1a245d7cc -[__NSDictionaryM enumerateKeysAndObjectsWithOptions:usingBlock:] + 288 (NSDictionaryM.m:271) 8 UIKitCore 0x1a948e6bc -[UIViewKeyframeAnimationState pop] + 376 (UIView.m:2955) 9 UIKitCore 0x1a7bc40e8 +[UIViewAnimationState popAnimationState] + 60 (UIView.m:1250) 10 UIKitCore 0x1a94acc44 +[UIView(UIViewAnimationWithBlocks) _setupAnimationWithDuration:delay:view:options:factory:animations:start:animationStateGenerator:completion:] + 684 (UIView.m:17669) 11 UIKitCore 0x1a94ae334 +[UIView(UIViewKeyframeAnimations) animateKeyframesWithDuration:delay:options:animations:completion:] + 224 (UIView.m:17945) 12 MyApp 0x102c78dec static UIView.animateNestedKeyframe(withRelativeStartTime:relativeDuration:animations:) + 208 (UIView+AnimateNestedKeyframe.swift:10) 13 MyApp 0x102aef3c0 closure #1 in DismissPlayerAnimationController.slideDownBelowTabBarTransitionAnimator(using:) + 156 (DismissPlayerAnimationController.swift:229) 14 MyApp 0x102a2d3d4 <deduplicated_symbol> + 28 15 UIKitCore 0x1a7d5ae5c -[UIViewPropertyAnimator _runAnimations] + 172 (UIViewPropertyAnimator.m:2123) 16 UIKitCore 0x1a83e1594 __49-[UIViewPropertyAnimator startAnimationAsPaused:]_block_invoke_3 + 92 (UIViewPropertyAnimator.m:3557) 17 UIKitCore 0x1a83e1464 __49-[UIViewPropertyAnimator startAnimationAsPaused:]_block_invoke + 96 (UIViewPropertyAnimator.m:3547) 18 UIKitCore 0x1a83e1518 __49-[UIViewPropertyAnimator startAnimationAsPaused:]_block_invoke_2 + 144 (UIViewPropertyAnimator.m:3553) 19 UIKitCore 0x1a83e0e64 -[UIViewPropertyAnimator _setupAnimationTracking:] + 100 (UIViewPropertyAnimator.m:3510) 20 UIKitCore 0x1a83e1264 -[UIViewPropertyAnimator startAnimationAsPaused:] + 728 (UIViewPropertyAnimator.m:3610) 21 UIKitCore 0x1a83de42c -[UIViewPropertyAnimator pauseAnimation] + 68 (UIViewPropertyAnimator.m:2753) 22 UIKitCore 0x1a87d5328 -[UIPercentDrivenInteractiveTransition _startInterruptibleTransition:] + 244 (UIViewControllerTransitioning.m:982) 23 UIKitCore 0x1a87d5514 -[UIPercentDrivenInteractiveTransition startInteractiveTransition:] + 184 (UIViewControllerTransitioning.m:1012) 24 UIKitCore 0x1a7c7931c ___UIViewControllerTransitioningRunCustomTransitionWithRequest_block_invoke_3 + 152 (UIViewControllerTransitioning.m:1579) 25 UIKitCore 0x1a892aefc +[UIKeyboardSceneDelegate _pinInputViewsForKeyboardSceneDelegate:onBehalfOfResponder:duringBlock:] + 96 (UIKeyboardSceneDelegate.m:3518) 26 UIKitCore 0x1a7c79238 ___UIViewControllerTransitioningRunCustomTransitionWithRequest_block_invoke_2 + 236 (UIViewControllerTransitioning.m:1571) 27 UIKitCore 0x1a94ab4b8 +[UIView(Animation) _setAlongsideAnimations:toRunByEndOfBlock:animated:] + 188 (UIView.m:17089) 28 UIKitCore 0x1a7c79070 _UIViewControllerTransitioningRunCustomTransitionWithRequest + 556 (UIViewControllerTransitioning.m:1560) 29 UIKitCore 0x1a86cb7cc __77-[UIPresentationController runTransitionForCurrentStateAnimated:handoffData:]_block_invoke_3 + 1784 (UIPresentationController.m:1504) 30 UIKitCore 0x1a7c43888 -[_UIAfterCACommitBlock run] + 72 (_UIAfterCACommitQueue.m:137) 31 UIKitCore 0x1a7c437c0 -[_UIAfterCACommitQueue flush] + 168 (_UIAfterCACommitQueue.m:228) 32 UIKitCore 0x1a7c436d0 _runAfterCACommitDeferredBlocks + 260 (UIApplication.m:3297) 33 UIKitCore 0x1a7c43c34 _cleanUpAfterCAFlushAndRunDeferredBlocks + 80 (UIApplication.m:3275) 34 UIKitCore 0x1a7c1f104 _UIApplicationFlushCATransaction + 72 (UIApplication.m:3338) 35 UIKitCore 0x1a7c1f024 __setupUpdateSequence_block_invoke_2 + 352 (_UIUpdateScheduler.m:1634) 36 UIKitCore 0x1a7c2cee8 _UIUpdateSequenceRunNext + 128 (_UIUpdateSequence.mm:189) 37 UIKitCore 0x1a7c2c378 schedulerStepScheduledMainSectionContinue + 60 (_UIUpdateScheduler.m:1185) 38 UpdateCycle 0x28c58f5f8 UC::DriverCore::continueProcessing() + 84 (UCDriver.cc:288) 39 CoreFoundation 0x1a2323230 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 28 (CFRunLoop.c:2021) 40 CoreFoundation 0x1a23231a4 __CFRunLoopDoSource0 + 172 (CFRunLoop.c:2065) 41 CoreFoundation 0x1a2300c6c __CFRunLoopDoSources0 + 232 (CFRunLoop.c:2102) 42 CoreFoundation 0x1a22d68b0 __CFRunLoopRun + 820 (CFRunLoop.c:2983) 43 CoreFoundation 0x1a22d5c44 _CFRunLoopRunSpecificWithOptions + 532 (CFRunLoop.c:3462) 44 GraphicsServices 0x2416a2498 GSEventRunModal + 120 (GSEvent.c:2049) 45 UIKitCore 0x1a7c50ddc -[UIApplication _run] + 792 (UIApplication.m:3899) 46 UIKitCore 0x1a7bf5b0c UIApplicationMain + 336 (UIApplication.m:5574) // ...
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623
Activity
Jan ’26
CATiledLayer flashes and re-draws entirely when re-drawing a single tile
I have filed a bug report for this (FB17734946), but I'm posting it here verbatim in case others have the same issue and in hopes of getting attention from an Apple engineer sooner. When calling setNeedsDisplayInRect on a CATiledLayer - or a UIView whose backing layer is CATiledLayer - one would expect to re-draw only a region identified by the rect passed to the method. This is even written in the documentation for the class: "Regions of the layer may be invalidated using the setNeedsDisplayInRect: method however the update will be asynchronous. While the next display update will most likely not contain the updated content, a future update will." However, upon calling this method, CATiledLayer redraws whole contents instead of just the tile at the specified rect, and it flashes when doing so. It behaves exactly the same as if one had called setNeedsDisplay without passing any rect; all contents are cleared and re-drawn again. I'm 100% sure I've passed in the correct rect of the exact tile that I need to redraw. I have even tried passing much smaller rects, but still the same. (And yes, the rect I've passed accounts for the current level of detail.) I have found this GitHub repo https://github.com/frankus/NetPhotoScroller, which based on discussion from here https://forums.macrumors.com/threads/catiledlayer-blanks-out-tiles-when-redrawing.1333948/ aims at solving these issues by using two private methods on CATiledLayer class: (void)setNeedsDisplayInRect:(CGRect)r levelOfDetail:(int)level; (BOOL)canDrawRect:(CGRect)rect levelOfDetail:(int)level; I have explored the repo in detail, however I wasn't able to test exactly this code from the GitHub repo. I have tried using those two private methods myself (through an Objective-C class that defines the methods in the header file and then a swift class which inherits it), but I couldn't solve the issue; the flashing and the full re-draw is still there. After doing a lot of research, the conclusion seems to be that one cannot use CATiledLayer with contents that are downloaded remotely, on demand, as tiles are being requested. I have, however, found one interesting thing which seems to work so far: before calling setNeedsDisplayInRect (or just setNeedsDisplay, as they behave the same for CATiledLayer in my testing), cache the current layer's contents, and after calling setNeedsDisplay (or setNeedsDisplayInRect), restore the contents back to the layer. This prevents flashing and preserves any tiles that were drawn at the time of the re-draw. let c = tiledLayer.contents tiledLayer.setNeedsDisplay(tileRect) tiledLayer.contents = c However! Docs clearly state the warning: Do not attempt to directly modify the contents property of a CATiledLayer object. Doing so disables the ability of a tiled layer to asynchronously provide tiled content, effectively turning the layer into a regular CALayer object. I believe this message implies modifying the contents property with some raw content, like image data, and that it may be safe to re-apply the existing contents (which are in my testing of type CAImageProvider) -- but I can't rely on an implementation detail in my production app. I have tested this and confirmed that the bug appears on: iPhone 14 Pro, iOS 18.5 iPhone 13 Pro, iOS 17.5.1 iPhone 5s, iOS 15.8.3 iPad Pro 1st gen, iPadOS 18.4.1 a couple simulator versions I can also confirm that the fix (to re-apply contents property) is also working properly on all these versions. Is this expected behavior, that tiled layer redraws itself entirely instead of redrawing specific tiles? Is it safe to modify contents of a CATiledLayer by re-applying the existing contents? If not, is there an alternative to avoid flashing?
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204
Activity
May ’25
Why does CADisplayLink of an external UIScreen drift in time?
I am using Apple's original Lightning Digital AV-adapter (Lightning-to-HDMI dongle) to connect my iPhone to an external display via a HDMI cable. I need to synchronize rendering with the external display's refresh rate, so I create a new CADisplayLink tied to the external display's UIScreen: UIScreen.screens[externalDisplayIdx].displayLink(withTarget:, selector:). The callback is being called regularly, but with increasing delay relative to the CADisplayLink.timestamp, so the next time the callback is called, I have less and less time to draw the next frame (see the snippet below). Assuming 60 FPS, the value of secondsTillDeadline starts at an arbitrary value in the range of approx -0.0001 to 0.0166667, and then it slowly decreases towards zero (and for a brief period it goes into small negative numbers). Once it reaches zero, it flips back to 0.0166667 and continues to decrease again. This cycle repeats indefinitely. Changing the external display's resolution (UIScreen's mode) or the CADisplayLink's preferredFrameRateRange to a lower FPS does not seem to have any effect on the temporal drifting (even the rate of change seem to be the same). When I create a new CADisplayLink for the iPhone's main screen, the value of secondsTillDeadline is stable, it does not drift and it is very close to 0.0166667, as expected. Is this drift caused by the external monitor or by Apple's Lightning-to-HDMI dongle ...or is the problem somewhere else? Can the drifting be stopped? func onDisplayLinkUpdate(displayLink: CADisplayLink) { // Gradually decreases from 0.01667 to -0.0001, then flips back to 0.01667 and continues to decrease let secondsTillDeadline = displayLink.targetTimestamp - CACurrentMediaTime() }
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472
Activity
Aug ’25
Core Text incremental redraw glitch: overlapping glyphs during editing
During editing in Pages (or Word) I am getting these glitches (see attachment). Started after the last update to Mac OS 26.3 (beta) Also removed 2 recent instalments (Blackhole audio driver and kDrive/Infomaniak, but trouble is still there. 27" iMac 2020 (Intel) i7 3,8 Ghz AMD Radeon Pro 5500 XT 8 GB 24 GB RAM macOS Tahoe 26.3 (=beta) Tried restart in safe mode, checked fonts. Talked to aissistent to get a solution, but no ...) Thx for any advice, Pieter (not a developer so please kee pit simple 🙏🏻)
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544
Activity
Feb ’26
SwiftUI Transaction completion handler is being called unexpectedly
Unexpected SwiftUI Transaction Behavior This minimal example demonstrates an unexpected behavior in SwiftUI's Transaction API: var transaction = Transaction(animation: .none) transaction.addAnimationCompletion { print("This should not be called!") } The Issue The completion handler is called immediately after creation, even though the transaction was never used in any SwiftUI animation context (like withTransaction or other animation-related APIs). Expected vs Actual Behavior Expected: The completion handler should only be called after the transaction is actually used in a SwiftUI animation. Actual: The completion handler is called right after creation, regardless of whether the transaction is used or not. Current Workaround To avoid this, I'm forced to implement defensive programming: only creating transactions with completion handlers at the exact moment they're going to be used. This adds unnecessary complexity and goes against the intuitive usage of the Transactions API.
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138
Activity
Jun ’25
Animation Ghosting with animation-timeline on 120HZ ProMotion Devices
On iOS Devices with ProMotion (120HZ) if you animate Elements on your Page with animation-timeline you get Ghosting Effects. You can not see the Ghosting with a Simulator or on Screenshots, only on real Devices. To Reproduce I made a Minimal Example: https://codesandbox.io/p/sandbox/120hztest-xrwgtc When you scroll quickly on the Page with an iOS 120HZ Device (https://en.wikipedia.org/wiki/List_of_smartphones_with_a_high_refresh_rate_display) you will see ghosting on the Top of the right Element (animation-timeline) and no ghosting on the other animated Element. (I edited the Screenshot, to Illustrate how the Effect looks like, since it is only visible on the real Display)
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248
Activity
Jan ’26
Animation Help
Hello, I am trying to use matchedGeometryEffect to animate between an item in a list view and the item's detail view. Right now, I am getting an unwanted cross-fade animation as the view transitions. So the list item moves into place as it should with the modifier, but it fades out as its detail version fades in, which I do not want. I do not want any fading at all, just the movement from one component to the other. How do I stop this? Thanks.
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81
Activity
Jan ’26
Navigation Bar animation upon Tab change
Hi. Since Xcode 16 and/or iOS 18.0 (I upgraded at the same time), I have an strange effect in the lower (let's say) 20% section of the Navigation Bar when changing to another tab, and this independently if large titles are used or not. Mentioned section is brighter or darker than the rest of the Navigation Bar background, depending on which background tint is used. This effect lasts about 0.3 seconds, but is clearly visible, quite disturbing and new as of Xcode 16 and/or iOS 18.0. I use the code below in AppDelegate to get a gradient coloured Navigation Bar background. let appearance = UINavigationBarAppearance() UINavigationBar.appearance().standardAppearance = appearance UINavigationBar.appearance().compactAppearance = appearance UINavigationBar.appearance().scrollEdgeAppearance = appearance UINavigationBar.appearance().compactScrollEdgeAppearance = appearance If I don't use above code., the background color is filled and without gradient. Subject effect doesn't show in this case. The effect basically looks like when changing tab, the new Navigation Bar background doesn't clear right away, and keeps the background from the previous Navigation Bar for 0.3 seconds before new one Navigation Bar background is rendered. I spent quite some time on changing every possible setting, in code as well as storyboard ... no success so far. Any ideas how to disable this undesired animation?
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790
Activity
Oct ’25
UI freeze during layouting
One of our users reported a very strange bug where our app freezes and eventually crashes on some screen transitions. From different crash logs we could determine that the app freezes up when we call view.layoutIfNeeded() for animating constraint changes. It then gets killed by the watchdog 10 seconds later: Exception Type: EXC_CRASH (SIGKILL) Exception Codes: 0x0000000000000000, 0x0000000000000000 Termination Reason: FRONTBOARD 2343432205 <RBSTerminateContext| domain:10 code:0x8BADF00D explanation:scene-update watchdog transgression: app<bundleID(2A01F261-3554-44C0-B5A9-EBEB446484AD)>:6921 exhausted real (wall clock) time allowance of 10.00 seconds ProcessVisibility: Background ProcessState: Running WatchdogEvent: scene-update WatchdogVisibility: Background WatchdogCPUStatistics: ( "Elapsed total CPU time (seconds): 24.320 (user 18.860, system 5.460), 29% CPU", "Elapsed application CPU time (seconds): 10.630, 12% CPU" ) reportType:CrashLog maxTerminationResistance:Interactive> The crash stack trace looks slightly different, depending on the UI transition that is happening. Here are the two we observed so far. Both are triggered by the layoutIfNeeded() call. Thread 0 name: Dispatch queue: com.apple.main-thread Thread 0 Crashed: 0 CoreAutoLayout 0x1b09f90e4 -[NSISEngine valueForEngineVar:] + 8 1 UIKitCore 0x18f919478 -[_UIViewLayoutEngineRelativeAlignmentRectOriginCache origin] + 372 2 UIKitCore 0x18f918f18 -[UIView _nsis_center:bounds:inEngine:forLayoutGuide:] + 1372 3 UIKitCore 0x18f908e9c -[UIView(Geometry) _applyISEngineLayoutValuesToBoundsOnly:] + 248 4 UIKitCore 0x18f9089e0 -[UIView(Geometry) _resizeWithOldSuperviewSize:] + 148 5 CoreFoundation 0x18d0cd6a4 __NSARRAY_IS_CALLING_OUT_TO_A_BLOCK__ + 24 6 CoreFoundation 0x18d0cd584 -[__NSArrayM enumerateObjectsWithOptions:usingBlock:] + 432 7 UIKitCore 0x18f8e62b0 -[UIView(Geometry) resizeSubviewsWithOldSize:] + 128 8 UIKitCore 0x18f977194 -[UIView(AdditionalLayoutSupport) _is_layout] + 124 9 UIKitCore 0x18f976c2c -[UIView _updateConstraintsAsNecessaryAndApplyLayoutFromEngine] + 800 10 UIKitCore 0x18f903944 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 2728 11 QuartzCore 0x18ec15498 CA::Layer::layout_if_needed(CA::Transaction*) + 496 12 UIKitCore 0x18f940c10 -[UIView(Hierarchy) layoutBelowIfNeeded] + 312 Thread 0 name: Dispatch queue: com.apple.main-thread Thread 0 Crashed: 0 QuartzCore 0x18ec2cfe0 -[CALayer animationForKey:] + 176 1 UIKitCore 0x18fa5b258 UniqueAnimationKeyForLayer + 192 2 UIKitCore 0x18fa5ab7c __67-[_UIViewAdditiveAnimationAction runActionForKey:object:arguments:]_block_invoke_2 + 468 3 UIKitCore 0x18fa5ba5c -[_UIViewAdditiveAnimationAction runActionForKey:object:arguments:] + 1968 4 QuartzCore 0x18eb9e938 CA::Layer::set_bounds(CA::Rect const&, bool) + 428 5 QuartzCore 0x18eb9e760 -[CALayer setBounds:] + 132 6 UIKitCore 0x18f941770 -[UIView _backing_setBounds:] + 64 7 UIKitCore 0x18f940404 -[UIView(Geometry) setBounds:] + 340 8 UIKitCore 0x18f908f84 -[UIView(Geometry) _applyISEngineLayoutValuesToBoundsOnly:] + 480 9 UIKitCore 0x18f9089e0 -[UIView(Geometry) _resizeWithOldSuperviewSize:] + 148 10 CoreFoundation 0x18d0cd6a4 __NSARRAY_IS_CALLING_OUT_TO_A_BLOCK__ + 24 11 CoreFoundation 0x18d132488 -[__NSSingleObjectArrayI enumerateObjectsWithOptions:usingBlock:] + 92 12 UIKitCore 0x18f8e62b0 -[UIView(Geometry) resizeSubviewsWithOldSize:] + 128 13 UIKitCore 0x18f977194 -[UIView(AdditionalLayoutSupport) _is_layout] + 124 14 UIKitCore 0x18f976c2c -[UIView _updateConstraintsAsNecessaryAndApplyLayoutFromEngine] + 800 15 UIKitCore 0x18f916258 -[UIView(Hierarchy) layoutSubviews] + 204 16 UIKitCore 0x18f903814 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 2424 17 QuartzCore 0x18ec15498 CA::Layer::layout_if_needed(CA::Transaction*) + 496 18 UIKitCore 0x18f940c10 -[UIView(Hierarchy) layoutBelowIfNeeded] + 312 So far, we only know of one iPad Air M1 where this is happening. But we don't know how many users experience this issue without reporting it. Does anyone know what could cause Auto Layout or Core Animation to block in those calls? We have no clue so far...
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210
Activity
Apr ’25
How to obtain frame rate for iOS proMotion devices
Due to the release of ProMotion devices, the system may switch frame rates in certain scenarios, resulting in the loss of reference value for data collected through CADisplayLink callbacks at a fixed 60Hz frame rate. We cannot distinguish whether the slow callback of CADisplayLink is due to a stutter or a system switch in frame rate. I know Hitch Time Ratio, but I can't use this scheme for some reasons. How can I distinguish between stuck and frame rate gear shift in CADisplaylink callback? In iOS 15, CADisplayLink.preferredFrameRateRange.preferred always returns 0, while minimum and maximum do change. Can I use these minimum and maximum range values as criteria to distinguish between frame rate switching and stuttering?
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162
Activity
May ’25
How to calculate smoothness to replicate CALayerCornerCurve.continuous?
iOS 26 added smoothness to CIRoundedRectangleGenerator, for use with CIFilter.roundedRectangleGenerator. What should the smoothness value be to achieve the same corner curve as CALayerCornerCurve.continuous? Does it need to be calculated based on the extent size, if so, how?
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246
Activity
Jun ’25
STextField becomes blurry after layer transform on macOS 26 (Tahoe)
Hi everyone, After upgrading to macOS 26 (Tahoe) I’ve run into an issue: NSTextField becomes noticeably blurry when its parent layer is transformed (CATransform3D or CGAffineTransform). On macOS 15 (Sequoia) the exact same code worked fine — text stayed sharp. Interestingly, an NSImage backed by a PDF representation transforms without any problem and remains perfectly crisp, but labels do not. What I’ve tried so far Checked the contentsScale of the layers Setting magnificationFilter = .nearest Toggled shouldRasterize on/off and adjusted rasterizationScale Have there been any Core Animation or AppKit changes in macOS 26 that affect text rendering when transforming layers? What’s the recommended way now to keep NSTextField text sharp (similar to how vector PDF images behave) when scaling its parent layer? Any insights, best practices, or workarounds would be greatly appreciated. Thanks in advance!
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216
Activity
Sep ’25