Hi all, I've encountered a potential issue with how the winding order of geometry is handled when their transformations involve negative scaling. I created a simple test asset, a single triangle, to demonstrate this. The triangle's vertices are defined in a counter-clockwise ("right-handed") winding order, and its transform has a negative scale on the X-axis. According to the OpenUSD specification, this negative determinant in the transformation matrix should effectively reverse the winding order of the geometry: However, any given gprim's local-to-world transformation can flip its effective orientation, when it contains an odd number of negative scales. This condition can be reliably detected using the (Jacobian) determinant of the local-to-world transform: if the determinant is less than zero, then the gprim's orientation has been flipped, and therefore one must apply the opposite handedness rule when computing its surface normals (or just flip the computed normals) for the purposes of hidden surface detection and lighting calculations. When I view the asset in tools like Blender or Preview on macOS, it behaves as expected. The triangle's effective orientation is flipped to CW. However, when the same asset is viewed in Reality Composer Pro or with QuickLook on iOS, its effective orientation remains CCW. In other words, the triangle faces the opposite direction. My questions for the community and Apple are: Is this behavior in RealityKit a known issue? If this is a known issue, is there official guidance for DCC tools on how to export USDZ assets to ensure they appear correctly in the Apple ecosystem? Any insights or recommendations would be greatly appreciated.

For an app of mine I use CGSetDisplayTransferByTable to adjust the gamma table of the device. Since macOS Tahoe, these modifications are silently ignored. The display's actual gamma curve remains unchanged despite the API reporting successful completion. I've filed a FB for it a few weeks ago, and would love to figure out what could be causing this. FB18559786

In ARKit there is ARGeoAnchor, which lets you anchor content using latitude and longitude so objects stay fixed to a real-world location. Is there an equivalent feature in RealityKit? I want to place points in the world and make sure they don't move or drift after placement. If RealityKit doesn't support this directly, what is the recommended approach?

Hi team, I'm looking for the RealityKit debugger in Xcode 26 beta 3. I'm running a RealityKit app on my iPad running iPadOS 26 b3, but the debugger option is not there in Xcode.

Apple, please bring back SceneKit.

Hi everybody, I have 2 separate animations run.usdz and walk.usdz animation files which are loaded perfectly in Reality Composer Pro and in the RealityKit application. I want to gradually increase the speed of my player by switching blending weight values from 0.0 (walking) to 1.0 (full speed running). let rabbit = await RabbitBuilder.loadWalkingRabbit() let runningRabbit = await RabbitBuilder.loadRunningRabbit() rabbit.scale = SIMD3(0.05, 0.05, 0.05) runningRabbit.scale = SIMD3(0.05, 0.05, 0.05) let walkAnimation = rabbit.availableAnimations let runAnimation = runningRabbit.availableAnimations RabbitWalker.walkAnim = walkAnimation.first! RabbitWalker.runAnim = runAnimation.first! guard let walk = RabbitWalker.walkAnim, let run = RabbitWalker.runAnim else { return } let blendTree = BlendTreeAnimation<JointTransforms>( BlendTreeBlendNode(sources: [ BlendTreeSourceNode(source: walk.definition, name: "walk", weight: .value(1 - weight)), BlendTreeSourceNode(source: run.definition, name: "run", weight: .value(weight)) ]), name: "rabbitLocomotion", repeatMode: .repeat, offset: TimeInterval(elapsed) ) // I have runtime error after executing this line: "Cannot add incompatible timeline type to blend tree." guard let resource = try? AnimationResource.generate(with: blendTree) else { return } entity.playAnimation(resource) static func loadWalkingRabbit() async -> Entity? { do { let scene = try await Entity(named: "Scene", in: realityKitEnvironmentBundle) guard let rabbit = await scene.findEntity(named: "RabbitWalk") else { return nil } await rabbit.removeFromParent() return rabbit } catch { return nil } } static func loadRunningRabbit() async -> Entity? { do { let scene = try await Entity(named: "Scene", in: realityKitEnvironmentBundle) guard let rabbit = await scene.findEntity(named: "RabbitRun") else { return nil } await rabbit.removeFromParent() return rabbit } catch { return nil } } But when I run this code I have this error; Cannot add incompatible timeline type to blend tree. By the way I have looked to developer's sample codes from here but I couldn't find any relevant BlendTreeAnimation sample which blends 2 animations. I would very happy if someone could direct me to a solution. Regards.

Attempting to bring up the access point yields the following error log: [GameCenterOverlayService] Failed to create GameOverlayUI Dashboard Remote Proxy [GameCenterOverlayService] Could not create endpoint for service name: com.apple.GameOverlayUI.dashboard-service [GameCenterOverlayService] Failed to create GameOverlayUI Dashboard Remote Proxy [GameCenterOverlayService] Could not create endpoint for service name: com.apple.GameOverlayUI.dashboard-service [GameCenterOverlayService] Failed to create GameOverlayUI Dashboard Remote Proxy [GameCenterOverlayService] Failed to create GameOverlayUI Dashboard Remote Proxy The same code (which is a single line setting 'active' to true) works on physical devices and on the simulator in iOS 18.6 I haven't been able to find any mention of this issue online. Any suggestions or help greatly appreciated.

Hi Apple team, Game Mode was introduced in iOS 18. To activate Game Mode, an app must include specific key-value pairs in its *.plist and be categorized as a "Game" on the App Store. My app (https://apps.apple.com/us/app/voidlink/id6747717070) works primarily as a self-hosted game streaming (PC->iPhone/iPad) client. Game Mode provides clear benefits in terms of latency and frame rate stability, but it can currently only be activated when running via Xcode or TestFlight. I am an individual iOS developer based in China, where an additional government license is required for apps to be listed under the "Game" category on the App Store. Obtaining such a license is very difficult for independent developers, so my app has been categorized under "Utilities" instead.(If move the app to game category, it will disappear from Chinese App Store immediately) Expectation / Suggestion: Please consider making Game Mode available as a local, user-controllable option on iOS18/26+, such as through a system “App Pool” where users can choose which apps to enable Game Mode for, regardless of App Store category. This would greatly benefit use cases like streaming clients, benchmarking tools, and remote play utilities, without requiring developers to reclassify their apps as “Games” on App Store.

We are developing a video processing app that applies CIFilter chains to video frames. To not force the user to keep the app foregrounded, we were happy to see the introduction of BGContinuedProcessingTask to continue processing when backgrounded. With iOS 26, I was excited to see the com.apple.developer.background-tasks.continued-processing.gpu entitlement, which should allow GPU access in the background. Even the article in the documentation provides "exporting video in a film-editing app" or "applying visual filters (HDR, etc) or compressing images for social media posts" as use cases. However, when I check BGTaskScheduler.shared.supportedResources.contains(.gpu) at runtime, it returns false on every iPhone I've tested (including iPhone 15 Pro and iPhone 16 Pro). From forum responses I've seen, it sounds like background GPU access is currently limited to iPad only. If that's the case, I have a few questions: Is this an intentional, permanent limitation — or is iPhone support planned for a future iOS release? What is the recommended approach for GPU-dependent background work on iPhone? My custom CIKernels are written in Metal (as Apple recommends since CIKL is deprecated), but Metal CIKernels cannot fall back to CPU rendering. This creates a situation where Apple's own deprecation guidance (migrate to Metal) conflicts with background processing realities (no GPU on iPhone). Should developers maintain deprecated CIKL kernel versions alongside Metal kernels purely as a CPU fallback for background execution? That feels like it defeats the purpose of the migration. It seems like a gap in the platform: the API exists, the entitlement exists, but the hardware support isn't there for the most common device category. Any clarity on Apple's direction here would be very helpful.

I've been thinking of bringing some older games back to the modern Mac. Rewriting old titles in Swift but using the original data files that assume use of non-rounded corners Windows. Many of these games require all the Window space of a 90 degree cornered Window. Can anyone point me at some useful workarounds or Is Apple simply deaf to the needs of this type of product?

Hello, In our game we enforce an age gate before showing Game Center sign‑in. Only after the user passes the age gate do we call GKLocalPlayer.localPlayer.authenticateHandler. The reason I’m asking is that we want to reliably detect if the game was launched from a Game Center activity in the Games app (iOS 26+). If the user prefers to enter via activities, we don’t want to miss that event during cold start. Our current proposal is: Register a GKLocalPlayerListener early in didFinishLaunchingWithOptions: so the app is ready to catch events. Queue any incoming events in our dispatcher. Only process those events after the user passes the age gate and authentication succeeds. My questions are: Does player:wantsToPlayGameActivity:completionHandler: ever fire before authentication, or only after the local player is authenticated? If it only fires after authentication, is our “register early but gate processing” approach the correct way to ensure we don’t miss activity launches? Is there any recommended pattern to distinguish “activity launch” vs. “normal launch” in this age‑gate scenario? We want to respect Apple’s age gate requirements, but also ensure activity launches are not lost if the user prefers that entry point. Sorry if this is a stupid question — I just want to be sure we’re following the right pattern. Thanks for any clarification or best‑practice guidance!

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I want to fade objects in and out, and while setting an entity's OpacityComponent works, animating it doesn't seem to do anything. In the following code the second sphere should fade out, but it keeps its initial opacity. On the other hand, the animation that changes its transform works. What am I doing wrong? class ViewController: NSViewController { override func loadView() { let arView = ARView(frame: NSScreen.main!.frame) let anchor = AnchorEntity(.world(transform: matrix_identity_float4x4)) arView.scene.addAnchor(anchor) let sphere = ModelEntity(mesh: .generateSphere(radius: 0.5)) anchor.addChild(sphere) sphere.components.set(OpacityComponent(opacity: 0.1)) let sphere2 = ModelEntity(mesh: .generateSphere(radius: 0.5)) sphere2.position = .init(x: 0.2, y: 0, z: 0) anchor.addChild(sphere2) sphere2.components.set(OpacityComponent(opacity: 0.1)) sphere.playAnimation(try! AnimationResource.makeActionAnimation(for: FromToByAction(to: 0, timing: .linear), duration: 1, bindTarget: .opacity)) sphere.playAnimation(try! AnimationResource.makeActionAnimation(for: FromToByAction(to: Transform(translation: SIMD3(x: 0.1, y: 0, z: 0)), timing: .linear), duration: 1, bindTarget: .transform)) view = arView } }

I noticed that MTLPixelFormat has this cases: case r32Float = 55 case rg32Float = 105 case rgba32Float = 125 But no case rgb32Float. What's the reason for such a discrimination?

I'm trying to convert my game from SceneKit to RealityKit. I noticed that even when the scene is static (nothing moves), RealityKit keeps using CPU. In SceneKit, CPU goes down to 0% with a static scene. With this simplest of games, RealityKit keeps using about 65% CPU: class ViewController: NSViewController { override func loadView() { view = ARView(frame: NSScreen.main!.frame) } } Is this expected or a bug? I created FB22125047.

Hi all, Wondering how I would go about creating a plugin/class to support a new (physical/hardware) device with the game controller framework? Between GCVirtualController on iOS and the "KeyboardAndMouseSupport.bundle" I see inside GameController.framework on my Mac, it looks like the framework must be designed to support this but I can't find any documentation. Thanks!

I’m trying to use EXR lightmaps to overlay baked lighting on top of a base texture in the RCP Shader Graph. When I multiply an EXR image set to Image(float) with an 8-bit base texture, the output becomes Image(float). I can’t connect that to the BaseColor input on the UnlitSurface node, since it only accepts Color3f. I expected to be able to use a Convert node between the Multiply node and the BaseColor input, but when I do that, the result becomes black and white instead of the expected outcome: the EXR multiplied with the base texture using a baseline value of 1, where values below 1 in the EXR would darken the base texture and values above 1 would brighten it. Is there any documentation on how to properly overlay a 32-bit EXR lightmap in the RCP Shader Graph, or is the black-and-white output from the Convert node a bug?

I am rewriting an unfinished SceneKit project as RealityKit (NonAR). As far as I can see, RealityKit is missing basic fog functionality? Fog was simple & easy to implement in SCeneKit (fogStartDistance / fogEndDistance / fogDensityExponent / fogColor). Are there any plans to implement something like this in RealityKit? Are there any simple workarounds?

In the CanyonCrosser example project, some RealityKit systems are implemented as classes while others are structs. What’s the reason for using different types?

I've been playing with the new GameSave API and cannot get it to work. I followed the 3-step instructions from the Developer video. Step 2, "Next, login to your Apple developer account and include this entitlement in the provisioning profile for your game." seems to be unnecessary, as Xcode set this for you when you do step 1 "First add the iCloud entitlement to your game." Running the app on my device and tapping "Load" starts the sync, then fails with the error "Couldn’t communicate with a helper application." I have no idea how to troubleshoot this. Every other time I've used CloudKit it has Just Worked™. Halp‽ Here is my example app: import Foundation import SwiftUI import GameSave @main struct GameSaveTestApp: App { var body: some Scene { WindowGroup { GameView() } } } struct GameView: View { @State private var loader = GameLoader() var body: some View { List { Button("Load") { loader.load() } Button("Finish sync") { Task { try? await loader.finish() } } } } } @Observable class GameLoader { var directory: GameSaveSyncedDirectory? func stateChanged() { let newState = withObservationTracking { directory?.state } onChange: { Task { @MainActor [weak self] in self?.stateChanged() } } print("State changed to \(newState?.description ?? "nil")") switch newState { case .error(let error): print("ERROR: \(error.localizedDescription)") default: _ = 0 // NOOP } } func load() { print("Opening gamesave directory") directory = GameSaveSyncedDirectory.openDirectory() stateChanged() } func finish() async throws { print("finishing syncing") await directory?.finishSyncing() } }