I'm updating our app to support metal 4, but the metal 4 types don't seem to get recognized when targeting simulator. Is it known if metal 4 will be supported in the near future, or am I setting up the app wrong?
Delve into the world of graphics and game development. Discuss creating stunning visuals, optimizing game mechanics, and share resources for game developers.
Selecting any option will automatically load the page
Post
Replies
Boosts
Views
Activity
Is it possible to start screen recording (through Control Center) without user prompt?
I mean to ask user permission for the first time and after that to start and stop recording programmatically only?
I need to record screen only for specific events.
Has anyone come across the issue that setting GKLocalPlayer.local.authenticateHandler breaks a RealityView's world tracking on iOS / iPadOS 18 beta 5?
I'm in the process of upgrading my app to make use of the much appreciated RealityView unification, using RealityView not only on visionOS but now also on iOS and iPadOS. In my RealityView, I enable world tracking on iOS like this:
content.camera = .worldTracking
However, device position and orientation were ignored (the camera remained static) and there was no camera pass-through. Then I discovered that the issue disappeared when I remove the line
GKLocalPlayer.local.authenticateHandler = { viewController, error in
// ... some more code ...
}
So I filed FB14731139 and hope that it will be resolved before the release of iOS / iPadOS 18.
Hi,
Introducing Swift Concurrency to my Metal app has been a bit challenging as Swift Concurrency is limited by the cooperative thread pool.
GPU work is obviously not CPU bound and can block forward moving progress, especially when using waitUntilCompleted on the command buffer. For concurrent render work this has the potential of under utilizing the CPU and even creating dead locks.
My question is, what is the Metal's teams general recommendation when it comes to concurrency? It seems to me that Dispatch or OperationQueues are still the preferred way for Metal bound tasks in order to gain maximum performance?
To integrate with Swift Concurrency my idea is to use continuations that kick off render jobs via Dispatch or Queues? Would this be the best solution to bridge async tasks with Metal work?
Thanks!
I would love to use Background GPU Access to do some video processing in the background.
However the documentation of BGContinuedProcessingTaskRequest.Resources.gpu clearly states:
Not all devices support background GPU use. For more information, see Performing long-running tasks on iOS and iPadOS.
Is there a list available of currently released devices that do (or don't) support GPU background usage? That would help to understand what part of our user base can use this feature. (And what hardware we need to test this on as developers.)
For example it seems that it isn't supported on an iPad Pro M1 with the current iOS 26 beta. The simulators also seem to not support the background GPU resource. So would be great to understand what hardware is capable of using this feature!
Hello, we are working on a iOS game project, as progress, the project grows larger and larger. Because we are using other game dependencies and libraries, here larger and larger refers to the whole project, and our source files integrated and compiled by Xcode are not many. Now, it seems we hit a bottleneck, when I add new files or functions to the previous files to implement a new feature, Xcode compile stucks(stops), it's Indexing | Initializing datastore forever, cannot produce a final build.
macOS 15.1, Xcode 16.2
Can you provide any solutions to solve this problem?
Also submitted Feedback ID #FB18432749
After updating to MacOS 26.1 I encountered an issue that Roblox tends to freeze quite often for 10 - 60 seconds at most, this is really annoying that it is doing this as i play the game a lot. My theory is that it is like a driver issue with metal or something, I have reinstalled MacOS, reinstalled the game and lowed the performance manually but nothing is working.
Wondering if you could help, when it will be fixed and if others are having the same issue.
Many thanks, William.
I am integrating MetalFX FrameInterpolator into a custom Unity RenderGraph–based render pipeline (C++ native plugin + C# render passes), and I am hitting the following assertion at runtime:
/MetalFXDebugError.h:29: failed assertion `Color texture width mismatch from descriptor'
What makes this confusing is that all input/output textures have the correct width and height, and they exactly match the values specified in the MTLFXFrameInterpolatorDescriptor.
Setup
Input resolution: 1024 x 512
Output resolution: 2048 x 1024
MTLFXTemporalScaler is created first and then passed into MTLFXFrameInterpolator
The TemporalScaler and FrameInterpolator descriptors use the same input/output sizes and formats
All Metal textures:
Have no parentTexture
Are 2D textures
Match the descriptor sizes exactly (verified via logging)
Texture bindings at encode time
frameInterpolator.colorTexture = mtlTexColor; // 1024 x 512
frameInterpolator.prevColorTexture = mtlTexPrevColor; // 1024 x 512
frameInterpolator.motionTexture = mtlTexMotion; // 1024 x 512
frameInterpolator.depthTexture = mtlTexDepth; // 1024 x 512
frameInterpolator.uiTexture = mtlTexUI; // 2048 x 1024
frameInterpolator.outputTexture = mtlTexOutput; // 2048 x 1024
All widths/heights are logged and match:
Color : 1024 x 512 (input)
PrevColor : 1024 x 512 (input)
Motion : 1024 x 512 (input)
Depth : 1024 x 512 (input)
UI : 2048 x 1024 (output)
Output : 2048 x 1024 (output)
The TemporalScaler works correctly on its own.
The assertion only occurs when using FrameInterpolator.
Important detail about colorTexture
Originally, colorTexture was copied from BuiltinRenderTextureType.CurrentActive.
After reading that this might violate MetalFX semantics, I changed the pipeline so that:
colorTexture now comes from a dedicated private RenderGraph texture
It is not the backbuffer
It is not a drawable
It is not used as a final output
It is created before UI rendering
Despite this, the assertion still occurs.
Question
Can uiTexture for MTLFXFrameInterpolator legally come from a texture copied from BuiltinRenderTextureType.CurrentActive?
More generally:
Are there additional hidden constraints on colorTexture / prevColorTexture (such as Metal usage, storageMode, aliasing, or hazard tracking) that could cause this assertion, even when sizes match?
Does FrameInterpolator require colorTexture and prevColorTexture to be created in a very specific way (e.g. non-aliased, ShaderRead usage, identical Metal resource properties)?
Any clarification on the exact semantic requirements for colorTexture, prevColorTexture, or uiTexture in MetalFX FrameInterpolator would be greatly appreciated.
I'm building a game with a client-server architecture. Using GKMatch.chooseBestHostingPlayer(_:) rarely works. When I started testing it today, it worked once at the very beginning, and since then it always succeeds on one client and returns nil on the other client. I'm testing with a Mac and an iPhone. Sometimes it fails on the Mac, sometimes on the iPhone. On the device that it succeeds on, the provided host can be the device itself or the other one.
I created FB9583628 in August 2021, but after the Feedback Assistant team replied that they are not able to reproduce it, the feedback never went forward.
import SceneKit
import GameKit
#if os(macOS)
typealias ViewController = NSViewController
#else
typealias ViewController = UIViewController
#endif
class GameViewController: ViewController, GKMatchmakerViewControllerDelegate, GKMatchDelegate {
var match: GKMatch?
var matchStarted = false
override func viewDidLoad() {
super.viewDidLoad()
GKLocalPlayer.local.authenticateHandler = authenticate
}
private func authenticate(_ viewController: ViewController?, _ error: Error?) {
#if os(macOS)
if let viewController = viewController {
presentAsSheet(viewController)
} else if let error = error {
print(error)
} else {
print("authenticated as \(GKLocalPlayer.local.gamePlayerID)")
let viewController = GKMatchmakerViewController(matchRequest: defaultMatchRequest())!
viewController.matchmakerDelegate = self
GKDialogController.shared().present(viewController)
}
#else
if let viewController = viewController {
present(viewController, animated: true)
} else if let error = error {
print(error)
} else {
print("authenticated as \(GKLocalPlayer.local.gamePlayerID)")
let viewController = GKMatchmakerViewController(matchRequest: defaultMatchRequest())!
viewController.matchmakerDelegate = self
present(viewController, animated: true)
}
#endif
}
private func defaultMatchRequest() -> GKMatchRequest {
let request = GKMatchRequest()
request.minPlayers = 2
request.maxPlayers = 2
request.defaultNumberOfPlayers = 2
request.inviteMessage = "Ciao!"
return request
}
func matchmakerViewControllerWasCancelled(_ viewController: GKMatchmakerViewController) {
print("cancelled")
}
func matchmakerViewController(_ viewController: GKMatchmakerViewController, didFailWithError error: Error) {
print(error)
}
func matchmakerViewController(_ viewController: GKMatchmakerViewController, didFind match: GKMatch) {
self.match = match
match.delegate = self
startMatch()
}
func match(_ match: GKMatch, player: GKPlayer, didChange state: GKPlayerConnectionState) {
print("\(player.gamePlayerID) changed state to \(String(describing: state))")
startMatch()
}
func startMatch() {
let match = match!
if matchStarted || match.expectedPlayerCount > 0 {
return
}
print("starting match with local player \(GKLocalPlayer.local.gamePlayerID) and remote players \(match.players.map({ $0.gamePlayerID }))")
match.chooseBestHostingPlayer { host in
print("host is \(String(describing: host?.gamePlayerID))")
}
}
}
I'm a newbee at Vulkan and Xcode.
I have my project on github https://github.com/flocela/OrangeSpider/
Whenever I run, two windows open instead of only one.
I added testing, which means I have an OrangeSpider.xctestplan in the OrangeSpider/TestsOrangeSpider/ folder.
This is my first time adding testing to an XCode project, so I think this may be where the problem is.
I also get this error message:
ViewBridge to RemoteViewService Terminated: Error Domain=com.apple.ViewBridge Code=18 "(null)" UserInfo={com.apple.ViewBridge.error.hint=this process disconnected remote view controller -- benign unless unexpected, com.apple.ViewBridge.error.description=NSViewBridgeErrorCanceled}
Topic:
Graphics & Games
SubTopic:
Metal
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
}
}
Can I use them in SK and do the animations work?
Thanks, Patrick
Hello everyone,
I must have missed something but why isn't there a depthAttachmentPixelFormat to the new Metal 4 MTL4RenderPipelineDescriptor, unlike the old MTLRenderPipelineDescriptor?
So how do you set the depth pixel format?
Thanks in advance!
I have really enjoyed looking through the code and videos related to Metal 4. Currently, my interest is to update a ReSTIR Project and take advantage of more robust ways to refit acceleration Structures and more powerful ways to access resources.
I am working in Swift and have encountered a couple of puzzles:
What is the 'accepted' way to create a MTL4BufferRange to store indices and vertices?
How do I properly rewrite Swift code to build and compact an Acceleration Structure?
I do realize that this is all in Beta and will happily look through Code Samples this Fall. If other guidance is available earlier, that would be fabulous!
Thank you
We have a released game in the App Store with Game Center Challenges. The challenges were working well in testing of the final version before the Game Center challenges went live. After release the activity that should take the player to the challenge in game results in this printout and we do not get informed by GKGameActivityListener of the activity happening in our code as we did before the Game Center challenges went live.
“Invalid game activity definition.
Failed to kick activity notification to GameKit. Error: Error Domain=GKErrorDomain Code=17 "(null)"”
Also, Game Center reports that the are no challenges in GKChallengeDefinition.all even though there are ongoing challenges.
The leaderboard results do get reported to Game Center though and show up as challenge entries in the Games app.
At the moment we are trying to figure out if this is a problem on our end or a Game Center server issue.
Topic:
Graphics & Games
SubTopic:
GameKit
Hello,
I recently watched the WWDC2025 session titled “Combine Metal 4 machine learning and graphics” (https://developer.apple.com/videos/play/wwdc2025/262/ ), and I’m very excited about the new Metal 4 features that integrate machine learning with graphics—such as neural ambient occlusion, shader-based ML inference, and the use of MTLTensor and MTL4MachineLearningCommandEncoder.
While the session includes helpful code snippets and a compelling debug demo (e.g., the neural ambient occlusion example), the implementation details are not fully shown, and I haven’t been able to find a complete, runnable sample project that demonstrates end-to-end integration of ML and rendering in Metal 4.
Would Apple be able to provide a full, working example—such as an Xcode project—that shows how to:
Export a model to an .mlpackage,
Convert it to an .mtlpackage,
Use MTL4MachineLearningCommandEncoder alongside render passes,
Or embed small neural networks directly in shaders using Shader ML?
Having such a sample would greatly help developers like me adopt these powerful new capabilities correctly and efficiently.
Thank you very much for your time and support!
Best regards,
I recently published my first game on the App Store. It uses SceneKit with a SpriteKit overlay. All crashes Xcode downloaded for it so far are related to some SpriteKit/SceneKit internals.
The most common crash is caused by SKCShapeNode::_NEW_copyRenderPathData. What could cause such a crash?
crash.crash
While developing this game (and the BoardGameKit framework that appears in the crash log) over the years I experienced many crashes presumably caused by the SpriteKit overlay (I opened a post SceneKit app randomly crashes with EXC_BAD_ACCESS in jet_context::set_fragment_texture about such a crash in September 2024), and other people on the internet also mention that they experience crashes when using SpriteKit as a SceneKit overlay. Should I use a separate SKView and lay it on top of SCNView rather than setting SCNView.overlaySKScene? That seemed to solve the crashes for a guy on stackoverflow, but is it also encouraged by Apple?
I know SceneKit is deprecated, but according to Apple critical bugs would still be fixed. Could this be considered a critical bug?
Hi! I watched the WWDC25 session "Bring your SceneKit project to RealityKit" which seemed like a great resource for those of us transitioning from the now-deprecated SceneKit framework. The session mentioned that the full sample code for the project would be available to download, but I haven't been able to find it in the Code section of the video page or in the Sample Code Library.
Has the sample code been released yet? Having the project code would make it much easier to follow along with the RealityKit changes shown in the video. Thanks again for the great session.
Breaking Through PolySpatial's ~8k Object Limit – Seeking Alternative Approaches for Large-Scale Digital Twins
Confirmed: PolySpatial make Doubles MeshFilter Count – Hard Limit at ~8k Active Objects (15.9k Total)
Project Context & Research Goals
I’m developing an industrial digital twin application for Apple Vision Pro using Unity’s PolySpatial framework (RealityKit rendering in Unbounded_Volume mode). The scene contains complex factory environments with:
Production line equipment Many fragmented grid objects need to be merged.)
Dynamic product racks (state-switchable assets)
Animated worker avatars
To optimize performance, I’m systematically testing visionOS’s rendering capacity limits. Through controlled stress tests, I’ve identified a critical threshold:
Key Finding
When the total MeshFilter count reaches 15,970 (system baseline + 7,985 user-created objects × 2 due to PolySpatial cloning), the application crashes consistently. This suggests:
PolySpatial’s mirroring mechanism effectively doubles GameObject overhead
An apparent hard limit exists around ~8k active mesh objects in practice
Objectives for This Discussion
Verify if others have encountered similar limits with PolySpatial/RealityKit
Understand whether this is a:
Memory constraint (per-app allocation)
Render pipeline limit (Metal draw calls)
Unity-specific PolySpatial behavior
Explore optimization strategies beyond brute-force object reduction
Why This Matters
Industrial metaverse applications require rendering thousands of interactive objects . Confirming these limits will help our team:
Design safer content guidelines
Prioritize GPU instancing/LOD investments
Potentially contribute back to PolySpatial’s optimization
I’d appreciate insights from engineers who’ve:
Pushed similar large-scale scenes in visionOS
Worked around PolySpatial’s cloning overhead
Discovered alternative capacity limits (vertices/draw calls)
Hello,
I've been trying to leverage instanced rendering in RealityKit on visionOS but have not had success.
RealityKit states this is supported:
https://developer.apple.com/documentation/realitykit/validating-usd-files
https://developer.apple.com/videos/play/wwdc2021/10075/?time=1373
https://developer.apple.com/videos/play/wwdc2023/10099/?time=772
RealityKit Trace metrics
Validating instancing is working:
To test I made a base visionOS app with immersive space and the entity replaced with my test usdz file. I've been using the RealityKit Trace profiling template in xcode instruments in the immersive space and volume closed. This gets consistent draw call results.
If I have a single sphere mesh with one material I get one draw call, but the number of draw calls grows linearly with mesh count no matter how my entity is configured.
What I've tried
Create a test scene in blender, export with instancing enabled
Create a test scene in Reality Composer Pro using references
Author usda files by hand based on the OpenUSD spec
Programatically create a MeshResource with Contents at runtime
References
https://openusd.org/release/api/_usd__page__scenegraph_instancing.html
https://developer.apple.com/documentation/realitykit/meshresource
https://developer.apple.com/documentation/realitykit/meshresource/instance
Thank you