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Query GPU metrics
Hello! I'm a developer working on a plugin for the Elgato Stream Deck, called GPU Metrics. The plugin currently only works on Windows but I'd like to bring it to macOS. However, based on forum posts I've read (and StackOverflow) there isn't a very clear path to query GPU metrics like usage, temperature, used GPU memory, and power consumption. There are some tools out there that do similar things, but I wanted to see what would be the recommendation from Apple's engineering team to get this data via a public API. Requirements: Access GPU utilization, temperature, memory usage, power usage C/C++ based API for querying the metrics so I can expose the data to JavaScript via Node Addon No need to compatibile with Intel-based Macs, as Apple silicon will be fine for now Plugin GitHub Thank you! Noah
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140
May ’25
How to add and remove child entities to a rigged entity in RealityKit?
I am currently using RealityKit (perspective camera) to render a character in my swiftUI app. The character has customization such as clothing items and hair and all objects are properly weighted to the rig. The way the model is setup in Blender is like so: Groups of objects that will be swapped (ex: Shoes -> Shoes objects) and an armature. I then export it to usdc with all objects active. This is the resulting hierarchy: Before exporting for the animation (armature modifier applied), I simply had to store the Model entities and swap them in but now when I export with the Armature Modifier applied, so that animations get exported, the ModelComponent gets flattened to the armature and swapping entities and applying new materials to them is no longer as simple. Here's a demo blend file and usdc export with a setup like mine, having an animated bone to swing a cube and sphere, to be swapped so that only one is visible https://www.dropbox.com/scl/fo/be2q6qcztc83z7c4gj1w0/AMapxWc_ip2KZ8oTOYDUMv8?rlkey=rcdaggcxq06dyen09mw5mqmem&st=bnc0d7j0&dl=0 This is how I'm loading the entity and removing a part, with the demo files import SwiftUI import RealityKit struct SwapDemoView: View { var body: some View { RealityView { content in let camera = PerspectiveCamera() camera.transform.translation = SIMD3(x: 0, y: 0.1, z: 3) guard let root = try? await Entity(named: "simpleSwapDemo") else { fatalError("simpleSwapDemo.usdc is not present") } print(root) // Get initial hierarchy guard let cube = root.findEntity(named: "Cube") else { fatalError("Entity cube doesn't exist") } cube.removeFromParent() // <-- Cube is still visible after removal print(root) // Get hierarchy to confirm removal of cube let resource = root.availableAnimations[0] root.playAnimation(resource.repeat()) content.add(root) content.add(camera) } .background(.white) } } And this is what the entity hierarchy looks like in RealityKit before cube removal ▿ 'root' : Entity, children: 1 ⟐ SynchronizationComponent ⟐ AnimationLibraryComponent ⟐ Transform ▿ 'Armature' : ModelEntity, children: 2 ⟐ SynchronizationComponent ⟐ ModelComponent ⟐ SkeletalPosesComponent ⟐ AnimationLibraryComponent ⟐ Transform ▿ 'Armature' : Entity ⟐ SynchronizationComponent ⟐ Transform ▿ 'Primitives' : Entity, children: 2 ⟐ SynchronizationComponent ⟐ Transform ▿ 'Sphere' : Entity, children: 1 ⟐ SynchronizationComponent ⟐ Transform ▿ 'Sphere' : Entity ⟐ SynchronizationComponent ⟐ Transform ▿ 'Cube' : Entity, children: 1 ⟐ SynchronizationComponent ⟐ Transform ▿ 'Cube' : Entity ⟐ SynchronizationComponent ⟐ Transform And here's the hierarchy after removal ▿ 'root' : Entity, children: 1 ⟐ SynchronizationComponent ⟐ AnimationLibraryComponent ⟐ Transform ▿ 'Armature' : ModelEntity, children: 2 ⟐ SynchronizationComponent ⟐ ModelComponent ⟐ SkeletalPosesComponent ⟐ AnimationLibraryComponent ⟐ Transform ▿ 'Armature' : Entity ⟐ SynchronizationComponent ⟐ Transform ▿ 'Primitives' : Entity, children: 1 ⟐ SynchronizationComponent ⟐ Transform ▿ 'Sphere' : Entity, children: 1 ⟐ SynchronizationComponent ⟐ Transform ▿ 'Sphere' : Entity ⟐ SynchronizationComponent ⟐ Transform And this is the result: What's the best practice here? Should animation be exported separately and then applied to the skeleton? If so, how is that achieved? I'm not really sure how to proceed here.
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141
May ’25
Building Game Porting Toolkit on Sequoia
Like many folks here, I've recently attempted to build Apple's Game Porting Toolkit on my machine and ran into compiler errors, but instead of going the usual route of downloading the prebuilt package (kindly provided by GCenX), I decided to see if I could force it to build (since it was obviously buildable at some point). Down below is the list of things I had to do to make it work. Disclaimer: There are several dirty hacks I had to attempt to force the system to do what I needed. Use at your own risk. Don't forget to run all brew commands from a Rosetta prompt: arch -x86_64 zsh Install openssl This one is easy. Just run brew tap rbenv/tap brew install rbenv/tap/openssl@1.1 Install Command Line Tools 15.1 This specific version is required since newer versions come with the linker that is not compatible with the custom compiler (game-porting-toolkit-compiler) that GPTK is using. However, by default 15.1 tools won't install on Sequoia since the installer complains that macOS version is too new. Obviously, Apple has their reasons to not allow this, but all we need is a compiler which should be mostly indifferent to the OS version. To trick the installer, we need to change OS requirement of the installer package. You can do it in four easy steps: Copy Command Line Tools.pkg from the mounted Command_Line_Tools_for_Xcode_15.1.dmg to some other directory. Expand the installer package: pkgutil --expand "Command Line Tools.pkg" CLT You might be prompted to install Command Line Tools when you call pkgutil, just install any version. Go to the newly created CLT folder and edit the Distribution file (it may appear as executable but it's just an xml). You would want to change allowed-os-versions to something greater than 15. Removing this section altogether might also work. When done, re-wrap the package: pkgutil --flatten CLT "Command Line Tools 2.pkg" Congratulations, now you should be able to install 15.1 tools on your OS! If you had to install newer Command Line Tools for pkgutil, delete them before installing 15.1: sudo rm -rf /Library/Developer/CommandLineTools Next step is to make Homebrew accept the outdated 15.1 tools, as by default it'll complain that they're outdated or corrupted. To shut it up, open /usr/local/Homebrew/Library/Homebrew/extend/os/Mac/diagnostic.rb and remove references to check_if_supported_sdk_available from a couple of fatal build check collections. Note - by default, Homebrew will auto-update on any invocation, which will overwrite any changes you've made to its internals. To disable this behavior, before running any brew commands in the terminal, run export HOMEBREW_NO_AUTO_UPDATE=1 After these manipulations, Homebrew might still complain about outdated Command Line Tools, but it won't be a fatal error anymore. Finally, we need to downgrade MinGW to 11.0.1, since the latest version spits out compiler errors when compiling Wine. Unfortunately, Homebrew does a bad job tracking versions of MinGW, so there is no automatic way to do it. Instead, you have to manually download and install old MinGW 11.0.1 formula from the Homebrew git repository. I used the commit from Sep 16, 2023: https://github.com/Homebrew/homebrew-core/blob/b95f4f9491394af667943bd92b081046ba3406f2/Formula/m/mingw-w64.rb Download the file above, save it in your current working directory, and then run brew install ./mingw-w64.rb If you had a newer version of MinGW already installed from the previous build attempts, you can unlink it before installing the one above: brew unlink mingw-w64 With Command Line Tools 15.1 and MinGW 11.0.1 you should now be able to build GPTK without errors: brew -v install apple/apple/game-porting-toolkit In the end, steps above worked for me, although more things could break in the future. I'm leaving the instructions here just to show that it's still possible to build GPTK manually instead of relying on third parties, but with all the hoops I had to jump through I can't really recommend it.
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763
Mar ’25
Support for clock() shader instruction in MSL similar to VK_KHR_shader_clock instructions
Hi, seems MSL is missing support for a clock() shader instruction available in other graphics APIs like Vulkan or OpenGL for example.. useful for counting cost in number of clock cycles of some code insider shader with much finer granularity than launching a micro kernel with same instructions and measuring cycles cost from CPU.. also useful for MoltenVK to support that extensions.. thanks..
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163
Apr ’25
macOS 26 Games app – Achievement description shows incorrect text before unlocking
Hello, I found an issue with the Games app on macOS 26 (Tahoe) when viewing achievements: In App Store Connect, each achievement has different values set for the pre-earned description and the post-earned description. When testing with GameKit directly (GKAchievementDescription), both values are returned correctly. However, in the macOS Games app, the post-earned description is shown even before the achievement is earned. This seems to be a display issue specific to the Games app on macOS. Could you confirm if this is a known bug in the Games app, or if there is a reason why pre-earned descriptions are not being shown? Thank you.
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475
Sep ’25
请问Game Center的数据保存逻辑
我们想在游戏类 App 内接入 Game Center。用户可以在游戏内创建多个角色,若用户在游戏内创建了2个角色:角色1、角色2,请问: 当用户将角色1与 Game Center 绑定后,数据将上报至 Game Center。此时玩家想要将角色1与 Game Center 解除绑定,解绑后,再将角色2与 Game Center 绑定。那么这时角色1的数据是留存在 Game Center 中,还是将被移除?
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324
Oct ’25
How does Game Kit offline leaderboard submission work?
I do not understand how offline leaderboard submission is supposed to work in Game Kit: While the documentation briefly states that offline submission is supported, how is that even possible when you first have to fetch a leaderboard object in order to then call its submitScore function? How can I get the leaderboard object in the first place when offline? Can anyone enlighten me how this works? Or maybe point me to some relevant documentation?
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397
Dec ’25
Threadgroup memory for fragment shader
Hello I am trying to get thread group memory access in fragment shader. In essence, I would like to have all the fragments in a tile to bitwiseOR some value. My idea was to use simd_or across the SIMD group, then make each SIMD group thread 0 to atomic or the value into thread group memory. Finally very first thread of the tile would be tasked with writing the value down to texture with write access. Now, I can allocate the thread group memory argument to the fragment function all right. MTLRenderEncoder has setThreadgroupMemoryLength call, which I am using the following way [renderEncoder setThreagroupMemoryLength: 16 offset: 0 atIndex:0] Unfortunately, all I am getting is the following error (runtime assertion) -[MTLDebugRenderCommandEncoder setThreadgroupMemoryLength:offset:atIndex:]:3487: failed assertion Set Threadgroup Memory Length Validation offset + length(16) must be <= threadgroupMemoryLength(0).` What I am doing wrong? How I can get thread group memory in the fragment shader? I know I could use tile shading and compute function but the problem is that here I really like to use fragment stuff. Will be grateful for help.
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115
Apr ’25
The App Store purchase button disappears when another window approaches
Since macOS 15.3.2, we have observed that when another window is moved near the App Store's install button, the button disappears. We have attached a related video in the Feedback submission here https://feedbackassistant.apple.com/feedback/20444423 Our application overlays a transparent, watermark-window on top of the system window, which causes the install button in the App Store to be hidden when a user attempts to install an application.Could you advise on how to avoid this issue?
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237
Nov ’25
GKAccessPoint triggerAccessPointWithState handler not invoked on iOS 26.0 and iOS 15.8.4
GKAccessPoint triggerAccessPointWithState handler not invoked on iOS 26.0 and iOS 15.8.4 Incorrect/Unexpected Behaviour: When calling [GKAccessPoint.shared triggerAccessPointWithState:GKGameCenterViewControllerStateAchievements handler:^{}] on a real device running iOS 26 beta (iOS 26), the overlay appears as expected, but the handler block is never called. This behavior also not working correctly on previous iOS versions(tested on iOS 15.8.4) Steps to Reproduce: Authenticate GKLocalPlayer Call triggerAccessPointWithState:handler: with a block that logs or performs logic Observe that overlay appears, but block is not executed Behavior: UI appears correctly Handler is not invoked at all Expected Result: The handler should fire immediately after the dashboard is shown. Actual Result: The handler is never called. Usecase: As GKGameCenterViewController is deprecated we are moving to GKAccesspoint but due to above functionality issue we are unable to. Environment: Device: iPhone 16, iPhone 7 iOS: 26.0 and iOS 15.8.4 Xcode: 26.0 beta and Xcode 16.4
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553
Oct ’25
Issues with installing Game Porting Toolkit 2.1
I am trying to install the Game Porting Toolkit 2.1 according to the Readme file provided with the toolkit. When I run the following command: WINEPREFIX=~/my-game-prefix brew --prefix game-porting-toolkit/bin/wine64 winecfg I get an error message: zsh: no such file or directory: /usr/local/opt/game-porting-toolkit/bin/wine64 I don't know how to resolve this. When I type in the command which brew , I get the path /usr/local/bin/brew What am I doing wrong?
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344
Apr ’25
Custom Cameras in RealityKit
Hi all, I've developed some code that enables an arcball camera interaction with my scene. I've done this using components and systems. The implementation feels a bit messy as I've got gesture code on my realityView, and then a bunch of other code that uses those gesture inputs in my component and system. Is there a demo app, or some example code that shows a nice way to encapsulate these things in to one item for custom cameras, something like Apple's .realityViewCameraControls(.orbit) If not can anyone recommend an approach to take?
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291
Oct ’25
Metal and Swift PM
I have run into an issue where I am trying to use atomic_float in a swift package but I cannot get things to compile because it appears that the Swift Package Manager doesn't support Metal 3 (atomic_float is Metal 3 functionality). Is there any way around this? I am using // swift-tools-version: 6.1 and my Metal code includes: #include <metal_stdlib> #include <metal_geometric> #include <metal_math> #include <metal_atomic> using namespace metal; kernel void test(device atomic_float* imageBuffer [[buffer(1)]], uint id [[ thread_position_in_grid ]]) { } But I get an error on the definition of atomic_float . Any help, one more importantly, where I could have found this information about this limitation, would be helpful. -RadBobby
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112
Apr ’25
ScreenCaptureKit recording output is corrupted when captureMicrophone is true
Hello everyone, I'm working on a screen recording app using ScreenCaptureKit and I've hit a strange issue. My app records the screen to an .mp4 file, and everything works perfectly until the .captureMicrophone is false In this case, I get a valid, playable .mp4 file. However, as soon as I try to enable the microphone by setting streamConfig.captureMicrophone = true, the recording seems to work, but the final .mp4 file is corrupted and cannot be played by QuickTime or any other player. This happens whether capturesAudio (app audio) is on or off. I've already added the "Privacy - Microphone Usage Description" (NSMicrophoneUsageDescription) to my Info.plist, so I don't think it's a permissions problem. I have my logic split into a ScreenRecorder class that manages state and a CaptureEngine that handles the SCStream. Here is how I'm configuring my SCStream: ScreenRecorder.swift // This is my main SCStreamConfiguration private var streamConfiguration: SCStreamConfiguration { var streamConfig = SCStreamConfiguration() // ... other HDR/preset config ... // These are the problem properties streamConfig.capturesAudio = isAudioCaptureEnabled streamConfig.captureMicrophone = isMicCaptureEnabled // breaks it if true streamConfig.excludesCurrentProcessAudio = false streamConfig.showsCursor = false if let region = selectedRegion, let display = currentDisplay { // My region/frame logic (works fine) let regionWidth = Int(region.frame.width) let regionHeight = Int(region.frame.height) streamConfig.width = regionWidth * scaleFactor streamConfig.height = regionHeight * scaleFactor // ... (sourceRect logic) ... } streamConfig.pixelFormat = kCVPixelFormatType_32BGRA streamConfig.colorSpaceName = CGColorSpace.sRGB streamConfig.minimumFrameInterval = CMTime(value: 1, timescale: 60) return streamConfig } And here is how I'm setting up the SCRecordingOutput that writes the file: ScreenRecorder.swift private func initRecordingOutput(for region: ScreenPickerManager.SelectedRegion) throws { let screeRecordingOutputURL = try RecordingWorkspace.createScreenRecordingVideoFile( in: workspaceURL, sessionIndex: sessionIndex ) let recordingConfiguration = SCRecordingOutputConfiguration() recordingConfiguration.outputURL = screeRecordingOutputURL recordingConfiguration.outputFileType = .mp4 recordingConfiguration.videoCodecType = .hevc let recordingOutput = SCRecordingOutput(configuration: recordingConfiguration, delegate: self) self.recordingOutput = recordingOutput } Finally, my CaptureEngine adds these to the SCStream: CaptureEngine.swift class CaptureEngine: NSObject, @unchecked Sendable { private(set) var stream: SCStream? private var streamOutput: CaptureEngineStreamOutput? // ... (dispatch queues) ... func startCapture(configuration: SCStreamConfiguration, filter: SCContentFilter, recordingOutput: SCRecordingOutput) async throws { let streamOutput = CaptureEngineStreamOutput() self.streamOutput = streamOutput do { stream = SCStream(filter: filter, configuration: configuration, delegate: streamOutput) // Add outputs for raw buffers (not used for file recording) try stream?.addStreamOutput(streamOutput, type: .screen, sampleHandlerQueue: videoSampleBufferQueue) try stream?.addStreamOutput(streamOutput, type: .audio, sampleHandlerQueue: audioSampleBufferQueue) try stream?.addStreamOutput(streamOutput, type: .microphone, sampleHandlerQueue: micSampleBufferQueue) // Add the file recording output try stream?.addRecordingOutput(recordingOutput) try await stream?.startCapture() } catch { logger.error("Failed to start capture: \(error.localizedDescription)") throw error } } // ... (stopCapture, etc.) ... } When I had the .captureMicrophone value to be false, I get a perfect .mp4 video playable everywhere, however, when its true, I am getting corrupted video which doesn't play at all :-
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452
3w
Achievement Banners Not always Showing
When running on my iPhone SE3 under IOS 18.4.1, achievement banners show as expected. The same code running on my iPad Air2 under IOS 15.8.4, achievement banners do not show, but they are accepted (as shown in the GameCenterViewController). The banners also don't show when running the simulator under iPhone 16 Pro Max under IOS 18.2 or simulator under iPhone SE3 under IOS 18.3. I haven't tried others. [Note that I clear the achievements each run during test so that I can duplicate this]
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116
May ’25
How can I assign priorities to my app’s GPU workloads?
My app has a number of heterogeneous GPU workloads that all run concurrently. Some of these should be executed with the highest priority because the app’s responsiveness depends on them, while others are triggered by file imports and the like which should have a low priority. If this was running on the CPU I’d assign the former User Interactive QoS and the latter Utility QoS. Is there an equivalent to this for GPU work?
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936
Jan ’26
Swift game sometimes runs on efficiency cores then snaps back to performance cores
I've been working on Swift game which is not yet launched or available for preview. The game works in such a way that it has idle CPU while the user is thinking and sustained max CPU and GPU on as many cores as possible when he makes a move. Rarely, due to OS activity or something else outside of my control (for example when dropping the OS curtain even if for just a bit then remove it), the game or some of its threads are moved to efficiency cores which results in major stuttering which persists precisely until the game is idle again at which point the game is moved back on performance cores - but if the player keeps making moves the stuttering simply won't go away and so I guess compuptation is locked onto efficiency cores. The issue does not reproduce on MacCatalyst on Intel. How do I tell Swift to avoid efficiency cores? BTW Swift and SceneKIT have AMAZING performance especially when compared to others.
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219
Mar ’25
iOS Matchmaker ViewController Info Button
I'm updating an existing distributed game to add turn-based matches. When the Matchmaker ViewController Info Button next to a game is pressed, the results vary: iOS 15.x - Button under avatar says "Accept Invite" or "View Game" (depending on if invite has already been accepted) iOS 18.x - Button always says "App Store" - I assume that means it would lead one to the App store to install the game. Both devices (iPad 15.x and iPhone 18.x) have the same version of the game installed. The results are the same when running in the simulator. When the game is released, I assume this button will work properly, no?
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407
Dec ’25
RealityKit SIMD3<Float> precision decreases with distance?
The farther away the center of a large entity is, the less accurate the positioning is? For example I am changing only the y-axis position of an entity that is tens of meters long, but i notice x and z drifting slowly the farther away the center of the entity is. I would not expect the x and z to move. It might be compounding rounding errors somewhere, or maybe the RealityKit engine is deciding not to be super precise about distant objects? Otherwise I just have a bug somewhere.
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618
Mar ’25