I'm writing a RealityKit/ARKit app that runs on iOS. Starting with Xcode 16.0 beta 1, at least through Xcode 16.1 beta 2 (16B5014f), in the iOS 18 simulator, my app randomly crashes in about 20% of app sessions the first time it attempts to present an ARView. The crashes seem to occur at multiple points within RealityKit and Metal. Below, I've included screenshots of the call stacks of the crashes, which occur as a result of both EXC_BAD_ACCESS and assertion failures within RealityKit. The app only crashes in the iOS 18 simulator, and does not crash in the iOS 17 simulator or earlier. The app only crashes in the simulator, and does not crash on a device running iOS 18. Before I investigate further, I'd appreciate it if an Apple engineer could give me a sense of if these crashes are most likely the result of known issues within RealityKit and/or the simulator, or if your opinion is that there are probably bugs in my app's code. I've submitted several feedback issues in the past, and I'd love to submit this issue too, but I expect that I would spend many hours attempting to create a repro case in a sample app. Understandably, I'd rather not spend this time if an Apple engineer could tell me this is a known issue, for example. Thank you.

For a UIKit app based on scenes (UIScene), is it safe to reference UserDefaults in code that is executed from UIApplicationDelegate/application(_: didFinishLaunchingWithOptions:) ? I've read that in iOS 15, there were undocumented scenarios involving app prewarming that would cause UserDefaults reads to fail within a window of time after device reboots, as described at https://christianselig.com/2024/10/beware-userdefaults/ The failure mode is that an app would be released, and months later, a small fraction of users would report failures consistent with UserDefaults reads unexpectedly returning nil, causing a loss of data. The user experience is bad, and debugging this behavior is then challenging because of how rarely it occurs. Apple's https://developer.apple.com/documentation/uikit/app_and_environment/responding_to_the_launch_of_your_app/about_the_app_launch_sequence#3894431 seems to suggest that prewarming only executes an app "up until, but not including when main() calls UIApplicationMain(_:_:_:_:), but https://stackoverflow.com/questions/71025205/ios-15-prewarming-causing-appwilllaunch-method-when-prewarm-is-done documents that UIApplicationDelegate/application(_: didFinishLaunchingWithOptions:) has in fact been observed executing during app prewarming in scene-based apps. So, my question: In an app based on scenes, if I'd like to reference UserDefaults within UIApplicationDelegate/application(_: didFinishLaunchingWithOptions:), when is it safe to do this? I'm guessing the answer is one of these: Never. Only in apps that don't support scenes. Only in iOS 16 or later. Only in IOS 17 or later. Is it guaranteed safe to reference UserDefaults in UIWindowSceneDelegate/scene(_:willConnectTo:options:) or later? Is there documentation from Apple regarding this issue? Thank you.

New in iOS 17.5 is UIImpactFeedbackGenerator/impactOccurred(at:), which generates haptic feedback at a specific screen location. https://developer.apple.com/documentation/uikit/uiimpactfeedbackgenerator/4403143-impactoccurred Which devices support this? How does this work if the Taptic Engine has a fixed physical location?

I've created a minimal iOS RealityKit/ARKit app with only this view controller: import UIKit import RealityKit import ARKit class ViewController: UIViewController { var arView: ARView! override func viewDidLoad() { super.viewDidLoad() arView = ARView(frame: view.bounds, cameraMode: .nonAR, automaticallyConfigureSession: true) arView.autoresizingMask = [.flexibleWidth, .flexibleHeight] view.addSubview(arView) } } When I run this app in the iOS 18.1 simulator using Xcode 16.1 beta 2 (16B5014f), RealityKit logs the warnings included below to the console. I see similar warnings on the device, running iOS 18.0. Should I be concerned about any of these warnings? Please let me know if I should submit feedback reporting this issue. Thank you. Could not locate file 'default-binaryarchive.metallib' in bundle. Registering library (/Library/Developer/CoreSimulator/Volumes/iOS_22B5045f/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS 18.1.simruntime/Contents/Resources/RuntimeRoot/System/Library/PrivateFrameworks/CoreRE.framework/default.metallib) that already exists in shader manager. Library will be overwritten. Could not resolve material name 'engine:BuiltinRenderGraphResources/AR/suFeatheringCreateMergedOcclusionMask.rematerial' in bundle at '/Users/drew/Library/Developer/CoreSimulator/Devices/6BCC578D-5046-49E6-B149-390576C7241D/data/Containers/Bundle/Application/75E15C63-F1D2-487F-A057-EBA2D45582C3/ARViewFailApp.app'. Loading via asset path. Could not resolve material name 'engine:BuiltinRenderGraphResources/AR/arKitPassthrough.rematerial' in bundle at '/Users/drew/Library/Developer/CoreSimulator/Devices/6BCC578D-5046-49E6-B149-390576C7241D/data/Containers/Bundle/Application/75E15C63-F1D2-487F-A057-EBA2D45582C3/ARViewFailApp.app'. Loading via asset path. Could not resolve material name 'engine:BuiltinRenderGraphResources/AR/arSegmentationComposite.rematerial' in bundle at '/Users/drew/Library/Developer/CoreSimulator/Devices/6BCC578D-5046-49E6-B149-390576C7241D/data/Containers/Bundle/Application/75E15C63-F1D2-487F-A057-EBA2D45582C3/ARViewFailApp.app'. Loading via asset path. Could not resolve material name 'engine:BuiltinRenderGraphResources/AR/arInPlacePostProcessCombinedPermute0.rematerial' in bundle at '/Users/drew/Library/Developer/CoreSimulator/Devices/6BCC578D-5046-49E6-B149-390576C7241D/data/Containers/Bundle/Application/75E15C63-F1D2-487F-A057-EBA2D45582C3/ARViewFailApp.app'. Loading via asset path. Could not resolve material name 'engine:BuiltinRenderGraphResources/AR/arInPlacePostProcessCombinedPermute1.rematerial' in bundle at '/Users/drew/Library/Developer/CoreSimulator/Devices/6BCC578D-5046-49E6-B149-390576C7241D/data/Containers/Bundle/Application/75E15C63-F1D2-487F-A057-EBA2D45582C3/ARViewFailApp.app'. Loading via asset path. Could not resolve material name 'engine:BuiltinRenderGraphResources/AR/arInPlacePostProcessCombinedPermute2.rematerial' in bundle at '/Users/drew/Library/Developer/CoreSimulator/Devices/6BCC578D-5046-49E6-B149-390576C7241D/data/Containers/Bundle/Application/75E15C63-F1D2-487F-A057-EBA2D45582C3/ARViewFailApp.app'. Loading via asset path. Could not resolve material name 'engine:BuiltinRenderGraphResources/AR/arInPlacePostProcessCombinedPermute3.rematerial' in bundle at '/Users/drew/Library/Developer/CoreSimulator/Devices/6BCC578D-5046-49E6-B149-390576C7241D/data/Containers/Bundle/Application/75E15C63-F1D2-487F-A057-EBA2D45582C3/ARViewFailApp.app'. Loading via asset path. Could not resolve material name 'engine:BuiltinRenderGraphResources/AR/arInPlacePostProcessCombinedPermute4.rematerial' in bundle at '/Users/drew/Library/Developer/CoreSimulator/Devices/6BCC578D-5046-49E6-B149-390576C7241D/data/Containers/Bundle/Application/75E15C63-F1D2-487F-A057-EBA2D45582C3/ARViewFailApp.app'. Loading via asset path. Could not resolve material name 'engine:BuiltinRenderGraphResources/AR/arInPlacePostProcessCombinedPermute5.rematerial' in bundle at '/Users/drew/Library/Developer/CoreSimulator/Devices/6BCC578D-5046-49E6-B149-390576C7241D/data/Containers/Bundle/Application/75E15C63-F1D2-487F-A057-EBA2D45582C3/ARViewFailApp.app'. Loading via asset path. Could not resolve material name 'engine:BuiltinRenderGraphResources/AR/arInPlacePostProcessCombinedPermute6.rematerial' in bundle at '/Users/drew/Library/Developer/CoreSimulator/Devices/6BCC578D-5046-49E6-B149-390576C7241D/data/Containers/Bundle/Application/75E15C63-F1D2-487F-A057-EBA2D45582C3/ARViewFailApp.app'. Loading via asset path. Could not resolve material name 'engine:BuiltinRenderGraphResources/AR/arInPlacePostProcessCombinedPermute7.rematerial' in bundle at '/Users/drew/Library/Developer/CoreSimulator/Devices/6BCC578D-5046-49E6-B149-390576C7241D/data/Containers/Bundle/Application/75E15C63-F1D2-487F-A057-EBA2D45582C3/ARViewFailApp.app'. Loading via asset path. Could not resolve material name 'engine:BuiltinRenderGraphResources/AR/arInPlacePostProcessCombinedPermute8.rematerial' in bundle at '/Users/drew/Library/Developer/CoreSimulator/Devices/6BCC578D-5046-49E6-B149-390576C7241D/data/Containers/Bundle/Application/75E15C63-F1D2-487F-A057-EBA2D45582C3/ARViewFailApp.app'. Loading via asset path. Could not resolve material name 'engine:BuiltinRenderGraphResources/AR/arInPlacePostProcessCombinedPermute9.rematerial' in bundle at '/Users/drew/Library/Developer/CoreSimulator/Devices/6BCC578D-5046-49E6-B149-390576C7241D/data/Containers/Bundle/Application/75E15C63-F1D2-487F-A057-EBA2D45582C3/ARViewFailApp.app'. Loading via asset path. Could not resolve material name 'engine:BuiltinRenderGraphResources/AR/arInPlacePostProcessCombinedPermute10.rematerial' in bundle at '/Users/drew/Library/Developer/CoreSimulator/Devices/6BCC578D-5046-49E6-B149-390576C7241D/data/Containers/Bundle/Application/75E15C63-F1D2-487F-A057-EBA2D45582C3/ARViewFailApp.app'. Loading via asset path. Could not resolve material name 'engine:BuiltinRenderGraphResources/AR/arInPlacePostProcessCombinedPermute11.rematerial' in bundle at '/Users/drew/Library/Developer/CoreSimulator/Devices/6BCC578D-5046-49E6-B149-390576C7241D/data/Containers/Bundle/Application/75E15C63-F1D2-487F-A057-EBA2D45582C3/ARViewFailApp.app'. Loading via asset path. Could not resolve material name 'engine:BuiltinRenderGraphResources/AR/arInPlacePostProcessCombinedPermute12.rematerial' in bundle at '/Users/drew/Library/Developer/CoreSimulator/Devices/6BCC578D-5046-49E6-B149-390576C7241D/data/Containers/Bundle/Application/75E15C63-F1D2-487F-A057-EBA2D45582C3/ARViewFailApp.app'. Loading via asset path. ... Compiler failed to build request makeRenderPipelineState failed [reading from a rendertarget is not supported]. Pipeline for technique meshShadowCasterProgrammableBlending failed compilation!

Using Reality Composer Pro 2.0, I created a simple shader graph that displays a texture on an unlit surface: On visionOS 2 beta, I can successfully use ShaderGraphMaterial(named:from:in:) to load that shader graph material and assign it to a model entity. However, on visionOS 1.2 and earlier, either in Simulator or on the device, ShaderGraphMaterial(named:from:in:) fails and I see the following logged to the console: If, using Reality Composer Pro 1.0, I experimentally open the same project and delete and recreate exactly the same nodes above, then ShaderGraphMaterial(named:from:in:) works as expected on visionOS 1.2. Is it a known issue that Reality Composer 2 can't be used with visionOS 1? Is this intentional behavior? I've submitted feedback as FB14828873, including a sample project and repro steps. If possible, I would appreciate guidance from an Apple engineer, like "This is a known issue for [list of node types]" or "Reality Composer Pro 2 is not supported for visionOS 1 development, please refer to [documentation]" or "We recommend [workaround]." Thank you.

In my app, I have an ARView that has cameraMode set to nonAR. I occasionally hide the ARView when it is not needed and reveal it again later. While the ARView is hidden, I'd like to pause the animation to save iPhone battery life. I'd also like to do this when I know that animation in my scene has paused and the contents of the view, although still visible, is static. This was possible using SceneKit, but I can't seem to find an equivalent way to do it using RealityKit. At least as of iOS 18, a hidden ARView with an empty scene appears to use approximately 30% of the CPU. How can I pause ARView so that it won't use the battery unnecessarily? Thank you for considering this question.

On App Store Connect, when a new TestFlight build is uploaded, it's no longer possible to add a group to the build. (FB14892147) I've seen this error message for 2+ hours. Other developers are reporting this issue: https://x.com/manuel_kehl/status/1826678066392793188 Apple's developer system status page doesn't report an outage: https://developer.apple.com/system-status/ Thank you for investigating this issue.

Will visionOS support SceneKit?

In iOS 18.0, UICollectionView/scrollToItem(at:at:animated:) causes UICollectionView to scroll with an awkward stuttered animation at about 4 frames per second on the device. This behavior is not observed in iOS 15, 16, or 17. I submitted FB13986989 about this issue 6 weeks ago when I first observed it in iOS 18 beta 1, but I have not received a response. The issue has not been fixed in iOS 18.0 beta 2, 3, or 4. Is this a known issue? Does Apple intend to fix it? Assuming Apple has not prioritized fixing this bug, could a UIKit engineer suggest a workaround? My app relies on scrollTo working properly and now looks awful on iOS 18. Thank you for any assistance you can provide.

Does visionOS 2 still prompt the user with a permission alert when a full immersive space is presented? In visionOS 1, the first time an app presented an immersive space, the user was prompted with an alert to grant permission. openImmersiveSpace would return an error code if the user opted not to grant permission. In visionOS 1, it was important to handle this case correctly. In visionOS 1, the Settings > Developer menu had an option to reset the immersive user's space permission prompting state so developers could test this interaction flow. In visionOS 2, I no longer see the full immersive space permissions alert. I can't remember if I saw it once, the first time visionOS 2.0 beta was installed, or if I never saw it at all. The Settings > Developer menu no longer has an option to reset the permission prompting state. I can't find any way to test the interaction flow in my app to make sure that it will work correctly for users. Does visionOS 2 no longer ask for full immersive space permission at all? I can't find this change documented anywhere. If visionOS 2 does prompt the user for permission, is there any way to reproduce and test this interaction flow so I can make sure my app handles it correctly? Thanks for taking the time to answer this question.

In Xcode 16.0 beta 3 (16A5202i) I'm trying to add a framework to a target. I'm clicking the '+' button under Target > General > Frameworks, Libraries, and Embedded Content: When I do this, the dialog that appears doesn't list any frameworks: I feel like I'm doing something wrong or missing something obvious. This issue is easy to reproduce by creating a new project in Xcode. I tried reverting using Xcode 15 to add the framework that way, but Xcode 15 is unable to load the project file that Xcode 16 wrote. Incidentally, Add Other > Add Package Dependency has no effect when selected: Assuming this is a bug I should submit feedback about, is there another method I can use in the meantime to add a framework to my target so I can continue working? This is blocking development. Thank you for any help you provide.

This question is about USD animations playing correctly in macOS Preview but not with RealityKit on visionOS. I have a USD file created with 3D Studio Max that contains mesh-based smoke animation: https://drive.google.com/file/d/1L7Jophgvw0u0USSv-_0fPGuCuJtapmzo/view (5.6 MB) Apple's macOS 14.5 Preview app is able to play the animation correctly: However, when a visionOS app uses RealityKit to load that same USD file in visionOS 2.0 beta 4, built with 16.0 beta 3 (16A5202i), and Entity/playAnimation is called, the animation does not play as expected: This same app is able to successfully play animation of a hierarchy of solid objects read from a different USD file. When I inspect the RealityKit entities loaded from the USD file, the ground plane entity is a ModelEntity, as expected, but the smoke entity type is Entity, with no associated geometry. Why is it that macOS Preview can play the animation in the file, but RealityKit cannot? Thank you for considering this question.

The WWDC24 video "Build a spatial drawing app with RealityKit" https://developer.apple.com/wwdc24/10104 at 12:04 includes a slide showing a Reality Composer Pro shader graph that features wonderful inline documentation comment boxes: Are shader graph inline comments a new feature that Reality Composer Pro supports? This would be extraordinarily useful, as complex shader graphs can be challenging to decipher. If so, how are inline shader graph comments created in Reality Composer Pro?

In RealityKit in visionOS 1.0 I'm perplexed that PhysicallyBasedMaterial and CustomMaterial have faceCulling properties but ShaderGraphMaterial does not. Is there some way to achieve front face culling in a shader graph without creating a separate mesh with reversed triangle vertex indices?

My visionOS app has a RealityView with an attachment containing SwiftUI controls, and occasionally the controls in the attachment don't respond to user interaction. Is this a known issue? Is there a workaround? Are RealityView attachments only intended to be output only? Using visionOS 1.0 beta 3 (Xcode 15 beta 8), I've reproduced this problem with a small standalone Xcode project. I submitted the issue as FB13143132 with lovingly hand-crafted artisan repro steps. The Xcode project is also available at https://github.com/drewolbrich/AttachmentControls Thank you for investigating this issue. Screenshot my use case: