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Game Porting Toolkit installation fails: CMake compatibility error in game-porting-toolkit-compiler
I'm encountering a build failure when trying to install the Game Porting Toolkit via Homebrew. The installation fails during the game-porting-toolkit-compiler dependency build phase with a CMake compatibility error. Error Message: CMake Error at CMakeLists.txt:3 (cmake_minimum_required): Compatibility with CMake < 3.5 has been removed from CMake. Update the VERSION argument <min> value. Or, use the <min>...<max> syntax to tell CMake that the project requires at least <min> but has been updated to work with policies introduced by <max> or earlier. Or, add -DCMAKE_POLICY_VERSION_MINIMUM=3.5 to try configuring anyway. -- Configuring incomplete, errors occurred! Environment: macOS: 15.6.1 (Sequoia) Homebrew: 5.0.1 CMake: 3.20.2 Architecture: x86_64 (via Rosetta) Formula: apple/apple/game-porting-toolkit-compiler v0.1 Source: crossover-sources-22.1.1.tar.gz Steps to Reproduce: Install x86_64 Homebrew for Rosetta compatibility Run: arch -x86_64 /usr/local/bin/brew install apple/apple/game-porting-toolkit Build fails during dependency installation Root Cause: The LLVM/Clang sources included in crossover-sources-22.1.1.tar.gz contain a CMakeLists.txt file that specifies a minimum CMake version lower than 3.5. Modern CMake versions (3.5+) have removed backward compatibility with these older version requirements. Potential Solutions: Update the Homebrew formula to patch the CMakeLists.txt with cmake_minimum_required(VERSION 3.5) or higher Update to newer CrossOver sources with updated CMake requirements Add the -DCMAKE_POLICY_VERSION_MINIMUM=3.5 flag to the CMake build command in the formula Is this a known issue? Are there plans to update the formula or the source package to resolve this compatibility problem? Any guidance on a workaround would be appreciated. Full log available at: /Users/kentarovadney/Library/Logs/Homebrew/game-porting-toolkit-compiler/02.cmake.log Thanks for any assistance!
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1k
Nov ’25
iOS Metal system delayed one Vsync period to really display the frame on the screen
View Layout Add the following views in a view controller: Label View A, with a subview of the same size: MTKView A View B, with a subview of the same size: MTKView B Refresh Rates of Each View The label view refreshes at 60fps (driven by CADisplayLink). MTKView A and B refresh at 15fps. MTKView Implementation Details The corresponding CAMetalLayer's maximumDrawableCount is set to 2, changed to double buffering. The scheduling mechanism is modified; drawing is not driven by the internal loop but is done manually. The draw call is triggered immediately upon receiving a frame. self.metalView.enableSetNeedsDisplay = NO; self.metalView.paused = YES; A new high-priority queue is created for drawing, instead of handling it on the main queue. MTKView Latency Tracking The GPU completion time T1 is observed through the addCompletedHandler callback of the CommandBuffer. The presentation time T2 of the frame is observed through the addPresentedHandler callback of the currentDrawable in MTKView. Testing shows that T2 - T1 > 16.6ms (the Vsync period at 60Hz). This means that after the GPU rendering in MTLView is finished, the frame is not actually displayed at the next Vsync instruction but only at the Vsync instruction after that. I believe there is an extra 16.6ms of latency here, which I want to eliminate by adjusting the rendering mechanism. Observation from Instruments From Instruments, the Surface presentation aligns with the above test results. After the Metal encoder finishes, the Surface in Display switches only after the next-next Vsync instruction. See the image in the link for details. Questions According to a beginner's understanding, after MTKView's GPU rendering is finished, the next Vsync instruction should officially display (make it visible). However, this is not what is observed. Does the subview MTKView need to wait for another Vsync cycle to be drawn to the actual display buffer? The label updates its text at 60fps, so the entire interface should be displayed at 60fps. Is the content of MTKView not synchronized when the display happens? Explanation of the Reasoning Behind Some MTKView Code Details Changing from the default triple buffering to double buffering helps reduce the latency introduced by rendering. Not using MTKView's own scheduling mechanism but using manual triggering of the draw method is because MTKView's own scheduling mechanism is driven by CADisplayLink. Therefore, if a frame falls within a Vsync window, it needs to wait for the next Vsync window to trigger the draw operation, which introduces waiting latency.
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604
Dec ’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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177
Apr ’25
Can a compute pipeline be as efficient as a render pipeline for rasterization?
I'm new to graphics and game design and I just wanted to know if a compute pipeline could be as efficient as a render pipeline for rasterization and an explanation on how and why. Also is it possible to manually perform rasterization with a render pipeline as in manipulate individual pixel data in a metal texture yourself but do it with a render pipeline?
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192
Mar ’26
RealityKit - How to change camera target in response of a touch event?
Hello, I’m porting my UIKit/SceneKit app to SwiftUI/RealityKit and I’m wondering how to change the camera target programmatically. I created a simple scene in Reality Composer Pro with two spheres. My goal is straightforward: when the user taps a sphere, the camera should look at it as the main target. Following Apple’s videos, I implemented the .gesture modifier and it is printing the tapped sphere correctly, but updating my targetEntity state doesn’t change anything, so the camera won't update its target. Is there a way to access the scene content at that level? Or what else should I do? Here’s my current code implementation: Thanks!
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336
Sep ’25
Showing 3D/AR content on multiple pages in iOS with RealityView
Hi. I'm trying to show 3D or AR content in multiple pages on an iOS app but I have found that if a RealityView is used earlier in a flow then future uses will never display the camera feed, even if those earlier uses do not use any spatial tracking. For example, in the following simplified view, the second page realityView will not display the camera feed even though the first view does not use it not start a tracking session. struct ContentView: View { var body: some View { NavigationStack { VStack { RealityView { content in content.camera = .virtual // showing model skipped for brevity } NavigationLink("Second Page") { RealityView { content in content.camera = .spatialTracking } } } } } } What is the way around this so that 3D content can be displayed in multiple places in the app without preventing AR content from working? I have also found the same problem when wrapping an ARView for use in SwiftUI.
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316
Feb ’26
'__abort_with_payload' from CompositorNonUI on visionOS 26.2 (device + simulator, Omniverse streaming)
I am developing a custom app for Apple Vision Pro using Compositor Services to stream content from NVIDIA Omniverse. The app is based on: https://github.com/NVIDIA-Omniverse/apple-configurator-sample Environment: Device: Apple Vision Pro OS Version: visionOS 26.2 Xcode Version: 26.2 The Issue: The application crashes hard (__abort_with_payload) in "libsystem_kernel.dylib" on Task 6 immediately after initialization. This appears to be a deliberate abort triggered by the compositor, not a typical crash. The issue occurs on both physical device and simulator. Important detail: The console output shows a specific CLIENT BUG assertion. By checking the metadata of the warning, I found that it is related to "Library: CompositorNonUI". Relevant console output before abort: Missed 'FrameLimiter' target of 90.0 Hz running compositor services to get IPD, FOV, etc fence tx observer 14f27 timed out after 0.600000 fence tx observer bc1b timed out after 0.600000 BUG IN CLIENT: For mixed reality experiences please use cp_drawable_compute_projection API
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148
Jan ’26
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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437
Dec ’25
App Crash in GameController when accessing GCKeyboard.coalesced on iPad
We are developing a hybrid iOS app where Angular content is rendered inside a WKWebView, hosted by a native Swift application. We use the GameController framework to detect whether an external Bluetooth keyboard is connected to an iPad. The following code is executed when the app enters the foreground and also when requested by the web layer: func keyboardStatusHandler(){ let isKeyboardConnected = GCKeyboard.coalesced != nil if(!isKeyboardConnected){ //sent status to Angular } else { //sent status to Angular } } Crash details We are seeing intermittent crashes on iPad with the following stack trace: Crashed: GCDeviceSession.HID 0 libobjc.A.dylib 0x7db8 objc_retain_x8 + 16 1 libsystem_blocks.dylib 0xfb8 void HelperBase<ExtendedInline>::copyCapture<(HelperBase<ExtendedInline>::BlockCaptureKind)3>(unsigned int) + 48 2 libsystem_blocks.dylib 0xbc4 HelperBase<GenericInline>::copyBlock(Block_layout*, Block_layout*) + 108 3 libsystem_blocks.dylib 0xc94 _call_copy_helpers_excp + 60 4 libsystem_blocks.dylib 0xef8 _Block_copy + 412 5 libdispatch.dylib 0x1a70 _dispatch_Block_copy + 32 6 libdispatch.dylib 0x792c dispatch_async + 56 7 libdispatch.dylib 0x792c dispatch_channel_async + 56 8 GameController 0xea6dc -[GCKeyboardInput _handleKeyboardEvent:] + 324 9 GameController 0x22508 __53-[_GCKeyboardEventHIDAdapter initWithSource:service:]_block_invoke + 376 10 GameController 0x11d30 -[_GCHIDEventSubject publishHIDEvent:] + 268 11 GameController 0xb79cc __40-[_GCHIDEventUIKitClient initWithQueue:]_block_invoke_3 + 44 12 libdispatch.dylib 0x1b584 _dispatch_client_callout + 16 13 libdispatch.dylib 0x12088 _dispatch_async_and_wait_invoke_and_complete_recurse + 272 14 libdispatch.dylib 0x8448 _dispatch_async_and_wait_f + 108 15 GameController 0xb7984 __40-[_GCHIDEventUIKitClient initWithQueue:]_block_invoke_2 + 132 16 GameController 0xb746c __48-[__GCHIDEventUIKitClient _initWithApplication:]_block_invoke + 256 17 UIKitCore 0x11fd394 __61-[UIEventFetcher _setHIDGameControllerEventObserver:onQueue:]_block_invoke_3 + 40 18 libdispatch.dylib 0x1aac _dispatch_call_block_and_release + 32 19 libdispatch.dylib 0x1b584 _dispatch_client_callout + 16 20 libdispatch.dylib 0xa2d0 _dispatch_lane_serial_drain + 740 21 libdispatch.dylib 0xadac _dispatch_lane_invoke + 388 22 libdispatch.dylib 0x151dc _dispatch_root_queue_drain_deferred_wlh + 292 23 libdispatch.dylib 0x14a60 _dispatch_workloop_worker_thread + 540 24 libsystem_pthread.dylib 0xa0c _pthread_wqthread + 292 25 libsystem_pthread.dylib 0xaac start_wqthread + 8 Observed scenarios Crash occurs when the app transitions from background to foreground Crash also occurs when the Angular layer requests keyboard status, triggering the same code path Questions Has anyone encountered crashes related to GCKeyboard.coalesced or GCKeyboardInput like this? Are there known issues with the GameController framework when querying keyboard state during app lifecycle transitions? Is there a recommended or safer way to detect external keyboard connection status on iPad (especially when using WKWebView)? Any insights, known platform issues, or suggested workarounds would be greatly appreciated. Thanks!
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Dec ’25
MPSMatrixRandom SEGFAULTs when ran in an async context
The following minimal snippet SEGFAULTS with SDK 26.0 and 26.1. Won't crash if I remove async from the enclosing function signature - but it's impractical in a real project. import Metal import MetalPerformanceShaders let SEED = UInt64(0x0) typealias T = Float16 /* Why ran in async context? Because global GPU object, and async makeMTLFunction, and async makeMTLComputePipelineState. Nevertheless, can trigger the bug without using global @MainActor let myGPU = MyGPU() */ @main struct CMDLine { static func main() async { let ptr = UnsafeMutablePointer<T>.allocate(capacity: 0) async let future: Void = randomFillOnGPU(ptr, count: 0) print("Main thread is playing around") await future print("Successfully reached the end.") } static func randomFillOnGPU(_ buf: UnsafeMutablePointer<T>, count destbufcount: Int) async { // let (device, queue) = await (myGPU.device, myGPU.commandqueue) let myGPU = MyGPU() let (device, queue) = (myGPU.device, myGPU.commandqueue) // Init MTLBuffer, async let makeFunction, makeComputePipelineState, etc. let tempDataType = MPSDataType.uInt32 let randfiller = MPSMatrixRandomMTGP32(device: device, destinationDataType: tempDataType, seed: Int(bitPattern:UInt(SEED))) print("randomFillOnGPU: successfully created MPSMatrixRandom.") // try await computePipelineState // ^ Crashes before this could return // Or in this minimal case, after randomFillOnGPU() returns // make encoder, set pso, dispatch, commit... } } actor MyGPU { let device : MTLDevice let commandqueue : MTLCommandQueue init() { guard let dev: MTLDevice = MPSGetPreferredDevice(.skipRemovable), let cq = dev.makeCommandQueue(), dev.supportsFamily(.apple6) || dev.supportsFamily(.mac2) else { print("Unable to get Metal Device! Exiting"); exit(EX_UNAVAILABLE) } print("Selected device: \(String(format: "%llX", dev.registryID))") self.device = dev self.commandqueue = cq print("myGPU: initialization complete.") } } See FB20916929. Apparently objc autorelease pool is releasing the wrong address during context switch (across suspension points). I wonder why such obvious case has not been caught before.
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Nov ’25
Compute kernel fails to compile when calling texture.read()
If I compile a compute kernel with a call to texture.read(), it fails with the following error: "Error Domain=AGXMetalG13X Code=3 "Encountered unlowered function call to air.get_read_sampler" UserInfo={NSLocalizedDescription=Encountered unlowered function call to air.get_read_sampler}." This error occurs on both macOS and iOS 26 Beta 5, but not when running on a simulator or in a playground. It does not occur on a macOS Sequoia VM. It occurs whether I use the old metal 3 or new metal 4 compilation method. A workaround would be to use a sampler, but according to the feature tables, all platforms support reading from textures of all formats. Below is a minimal example which produces the error: let device = MTLCreateSystemDefaultDevice()! let library = device.makeDefaultLibrary()! let computeFunction = library.makeFunction(name: "compute_test")! do { let pipeline = try device.makeComputePipelineState(function: computeFunction) debugPrint(pipeline) } catch { debugPrint("Metal 3 failed with error:\n\(error)") } #import <metal_stdlib> using namespace metal; kernel void compute_test(uint2 gid [[thread_position_in_grid]], texture2d<float, access::read> in [[texture(0)]], texture2d<float, access::write> out [[texture(1)]]) { out.write(in.read(gid), gid); } I filed feedback FB19530049.
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Aug ’25
Testing Achievements - Apple Documentation out of Date
New to achievements. I added them in App Store Connect and want to test them. Apple Documentation says this: "Before you begin testing your GameKit configuration, you need to enable Debug Mode. In Xcode, choose Product > Scheme > Edit Scheme. From the Run configuration, select Options and toggle Enable Debug Mode. To begin testing your achievement configuration, open the game Progress Manager. In Xcode, choose Debug > GameKit > Manage Game Progress." Sounds easy enough, but there is no "GameKit" under Debug in Xcode 16.2.
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May ’25
Can spatial scene function be used outside of the Photo App?
I'm new here so I don't know what's this function belongs to which topic... Sorry about that! I watched the WWDC stream and I am really interested in this function, I'm wondering if this function could be used in my apps. I looked up the document but I find it only support visionOS(i'm not sure about that, but I saw the demo is base on the visionOS)
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Jun ’25
Will OpenGL API and Drivers be removed after appleOS 26?
Hi, I am a Multimedia and Graphics researcher and I am wondering if OpenGL API and drivers will be removed after appleOS 26? macOS 26 iOS 26 iPadOS 26 visionOS 26 I am asking this because most of the libraries I use depends on OpenGL. Like CGAL, libigl, immediate mode ui, nanovg, nanogui, bullet physics. Transitioning from Vulkan and metal while using and learning those libraries is just not viable. I would like to ask you that. I am the sole developer and I just want to ask you that. Regards.
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241
Aug ’25
How to detect which entity was tapped?
Hi, I'm rewriting my game from SceneKit to RealityKit, and I'm having trouble implementing the following scenario: I tap on the iPhone screen to select an Entity that I want to drag. If an Entity was tapped, it should then be possible to drag it left, right, etc. SceneKit solution: func CGPointToSCNVector3(_ view: SCNView, depth: Float, point: CGPoint) -> SCNVector3 { let projectedOrigin = view.projectPoint(SCNVector3Make(0, 0, Float(depth))) let locationWithz = SCNVector3Make(Float(point.x), Float(point.y), Float(projectedOrigin.z)) return view.unprojectPoint(locationWithz) } and then I was calling: SCNView().hitTest(location, options: [SCNHitTestOption.firstFoundOnly:true]) the code was called inside of the UIPanGestureRecognizer in my UIViewController. Could I reuse that code or should I go with the SwiftUI approach - something like that: var body: some View { RealityView { .... } .gesture(TapGesture().onEnded { }) ? I already have this code: @State private var location: CGPoint? .onTapGesture { location in self.location = location } I'm trying to identify the entity that was tapped within the RealityView like that: RealityView { content in let box: ModelEntity = createBox() // for now there is only one box, however there will be many boxes content.add(box) let anchor = AnchorEntity(world: [0, 0, 0]) content.add(anchor) _ = content.subscribe(to: SceneEvents.Update.self) { event in //TODO: find tapped entity, so that it could be dragged inside of the DragGesture() } Any help would be appreciated. I also noticed that if I create a TapGesture like that: TapGesture(count: 1) .targetedToAnyEntity() and add it to my view using .gesture() then it is not triggered.
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297
Aug ’25
Does OLED burn-in affect iPad Pro displays, and should I implement a screen saver in my always-on app?
Hi everyone, I’m developing an iPad app that will be running continuously with the screen always on — similar to a restaurant ordering system. I understand that some of the newer iPad Pro models are equipped with OLED displays. I'm concerned about the potential risk of screen burn-in due to static UI elements being displayed for extended periods. Does burn-in occur on the OLED iPad Pro models under such usage? Would it be advisable to implement a screen saver or periodically animate/change parts of the UI to prevent this? Any insights or best practices would be greatly appreciated. Thank you!
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143
Jun ’25
Matchmaking issue on tvOS with GKMatchmakerViewController.Request
Hello ! We are working on a real-time 2-player online game targeting multiple Apple devices. The following issue only occurs on tvOS: When selecting matchmaking to connect with another random player, the native Game Center interface opens and begins the matchmaking process. Almost immediately after clicking "start", the following log appears in the console, and the matchmaking screen remains indefinitely without completing: Timeout while starting matching with request: <GKMatchRequestInternal 0x30d62f690> { defaultNumberOfPlayers : 0 isLateJoin : 0 localPlayerID : U:bea182d69b85f0839e3958742fbc4609 matchType : 0 maxPlayers : 2 minPlayers : 2 playerAttributes : 4294967295 playerGroup : 1 preloadedMatch : 0 recipientPlayerIDs : <__NSArrayM 0x3034ed5c0> {} recipients : <__NSArrayM 0x3034ee280> {} restrictToAutomatch : 0 version : 1 archivedSharePlayInviteeTokensFromProgrammaticInvite, inviteMessage, localizableInviteMessage, messagesBasedRecipients, properties, queueName, recipientProperties, rid, sessionToken : (null) } . Error: (null) However, as shown in the code snippet below, the task does not complete when the log appears. But when we manually cancel the matchmaking process, the "User cancel" log is correctly triggered. var gkMatchRequest = GKMatchRequest.Init(); gkMatchRequest.MinPlayers = 2; gkMatchRequest.MaxPlayers = 2; var matchRequestTask = GKMatchmakerViewController.Request(gkMatchRequest); matchRequestTask.ContinueWith(t => { Debug.LogException(t.Exception); }, TaskContinuationOptions.OnlyOnFaulted); matchRequestTask.ContinueWith(t => { Debug.Log("User cancel"); }, TaskContinuationOptions.OnlyOnCanceled); matchRequestTask.ContinueWith(t => { Debug.Log("Success"); }, TaskContinuationOptions.OnlyOnRanToCompletion); We have tested this on multiple Apple TV and network types (Wi-Fi, 5G, Ethernet), but we consistently encounter this bug along with the same log message. Could you please help us understand or resolve this issue? Thank you.
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Apr ’25
Game Porting Toolkit installation fails: CMake compatibility error in game-porting-toolkit-compiler
I'm encountering a build failure when trying to install the Game Porting Toolkit via Homebrew. The installation fails during the game-porting-toolkit-compiler dependency build phase with a CMake compatibility error. Error Message: CMake Error at CMakeLists.txt:3 (cmake_minimum_required): Compatibility with CMake < 3.5 has been removed from CMake. Update the VERSION argument <min> value. Or, use the <min>...<max> syntax to tell CMake that the project requires at least <min> but has been updated to work with policies introduced by <max> or earlier. Or, add -DCMAKE_POLICY_VERSION_MINIMUM=3.5 to try configuring anyway. -- Configuring incomplete, errors occurred! Environment: macOS: 15.6.1 (Sequoia) Homebrew: 5.0.1 CMake: 3.20.2 Architecture: x86_64 (via Rosetta) Formula: apple/apple/game-porting-toolkit-compiler v0.1 Source: crossover-sources-22.1.1.tar.gz Steps to Reproduce: Install x86_64 Homebrew for Rosetta compatibility Run: arch -x86_64 /usr/local/bin/brew install apple/apple/game-porting-toolkit Build fails during dependency installation Root Cause: The LLVM/Clang sources included in crossover-sources-22.1.1.tar.gz contain a CMakeLists.txt file that specifies a minimum CMake version lower than 3.5. Modern CMake versions (3.5+) have removed backward compatibility with these older version requirements. Potential Solutions: Update the Homebrew formula to patch the CMakeLists.txt with cmake_minimum_required(VERSION 3.5) or higher Update to newer CrossOver sources with updated CMake requirements Add the -DCMAKE_POLICY_VERSION_MINIMUM=3.5 flag to the CMake build command in the formula Is this a known issue? Are there plans to update the formula or the source package to resolve this compatibility problem? Any guidance on a workaround would be appreciated. Full log available at: /Users/kentarovadney/Library/Logs/Homebrew/game-porting-toolkit-compiler/02.cmake.log Thanks for any assistance!
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Activity
Nov ’25
iOS Metal system delayed one Vsync period to really display the frame on the screen
View Layout Add the following views in a view controller: Label View A, with a subview of the same size: MTKView A View B, with a subview of the same size: MTKView B Refresh Rates of Each View The label view refreshes at 60fps (driven by CADisplayLink). MTKView A and B refresh at 15fps. MTKView Implementation Details The corresponding CAMetalLayer's maximumDrawableCount is set to 2, changed to double buffering. The scheduling mechanism is modified; drawing is not driven by the internal loop but is done manually. The draw call is triggered immediately upon receiving a frame. self.metalView.enableSetNeedsDisplay = NO; self.metalView.paused = YES; A new high-priority queue is created for drawing, instead of handling it on the main queue. MTKView Latency Tracking The GPU completion time T1 is observed through the addCompletedHandler callback of the CommandBuffer. The presentation time T2 of the frame is observed through the addPresentedHandler callback of the currentDrawable in MTKView. Testing shows that T2 - T1 > 16.6ms (the Vsync period at 60Hz). This means that after the GPU rendering in MTLView is finished, the frame is not actually displayed at the next Vsync instruction but only at the Vsync instruction after that. I believe there is an extra 16.6ms of latency here, which I want to eliminate by adjusting the rendering mechanism. Observation from Instruments From Instruments, the Surface presentation aligns with the above test results. After the Metal encoder finishes, the Surface in Display switches only after the next-next Vsync instruction. See the image in the link for details. Questions According to a beginner's understanding, after MTKView's GPU rendering is finished, the next Vsync instruction should officially display (make it visible). However, this is not what is observed. Does the subview MTKView need to wait for another Vsync cycle to be drawn to the actual display buffer? The label updates its text at 60fps, so the entire interface should be displayed at 60fps. Is the content of MTKView not synchronized when the display happens? Explanation of the Reasoning Behind Some MTKView Code Details Changing from the default triple buffering to double buffering helps reduce the latency introduced by rendering. Not using MTKView's own scheduling mechanism but using manual triggering of the draw method is because MTKView's own scheduling mechanism is driven by CADisplayLink. Therefore, if a frame falls within a Vsync window, it needs to wait for the next Vsync window to trigger the draw operation, which introduces waiting latency.
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604
Activity
Dec ’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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177
Activity
Apr ’25
Can a compute pipeline be as efficient as a render pipeline for rasterization?
I'm new to graphics and game design and I just wanted to know if a compute pipeline could be as efficient as a render pipeline for rasterization and an explanation on how and why. Also is it possible to manually perform rasterization with a render pipeline as in manipulate individual pixel data in a metal texture yourself but do it with a render pipeline?
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192
Activity
Mar ’26
RealityKit - How to change camera target in response of a touch event?
Hello, I’m porting my UIKit/SceneKit app to SwiftUI/RealityKit and I’m wondering how to change the camera target programmatically. I created a simple scene in Reality Composer Pro with two spheres. My goal is straightforward: when the user taps a sphere, the camera should look at it as the main target. Following Apple’s videos, I implemented the .gesture modifier and it is printing the tapped sphere correctly, but updating my targetEntity state doesn’t change anything, so the camera won't update its target. Is there a way to access the scene content at that level? Or what else should I do? Here’s my current code implementation: Thanks!
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336
Activity
Sep ’25
Showing 3D/AR content on multiple pages in iOS with RealityView
Hi. I'm trying to show 3D or AR content in multiple pages on an iOS app but I have found that if a RealityView is used earlier in a flow then future uses will never display the camera feed, even if those earlier uses do not use any spatial tracking. For example, in the following simplified view, the second page realityView will not display the camera feed even though the first view does not use it not start a tracking session. struct ContentView: View { var body: some View { NavigationStack { VStack { RealityView { content in content.camera = .virtual // showing model skipped for brevity } NavigationLink("Second Page") { RealityView { content in content.camera = .spatialTracking } } } } } } What is the way around this so that 3D content can be displayed in multiple places in the app without preventing AR content from working? I have also found the same problem when wrapping an ARView for use in SwiftUI.
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316
Activity
Feb ’26
'__abort_with_payload' from CompositorNonUI on visionOS 26.2 (device + simulator, Omniverse streaming)
I am developing a custom app for Apple Vision Pro using Compositor Services to stream content from NVIDIA Omniverse. The app is based on: https://github.com/NVIDIA-Omniverse/apple-configurator-sample Environment: Device: Apple Vision Pro OS Version: visionOS 26.2 Xcode Version: 26.2 The Issue: The application crashes hard (__abort_with_payload) in "libsystem_kernel.dylib" on Task 6 immediately after initialization. This appears to be a deliberate abort triggered by the compositor, not a typical crash. The issue occurs on both physical device and simulator. Important detail: The console output shows a specific CLIENT BUG assertion. By checking the metadata of the warning, I found that it is related to "Library: CompositorNonUI". Relevant console output before abort: Missed 'FrameLimiter' target of 90.0 Hz running compositor services to get IPD, FOV, etc fence tx observer 14f27 timed out after 0.600000 fence tx observer bc1b timed out after 0.600000 BUG IN CLIENT: For mixed reality experiences please use cp_drawable_compute_projection API
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148
Activity
Jan ’26
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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437
Activity
Dec ’25
App Crash in GameController when accessing GCKeyboard.coalesced on iPad
We are developing a hybrid iOS app where Angular content is rendered inside a WKWebView, hosted by a native Swift application. We use the GameController framework to detect whether an external Bluetooth keyboard is connected to an iPad. The following code is executed when the app enters the foreground and also when requested by the web layer: func keyboardStatusHandler(){ let isKeyboardConnected = GCKeyboard.coalesced != nil if(!isKeyboardConnected){ //sent status to Angular } else { //sent status to Angular } } Crash details We are seeing intermittent crashes on iPad with the following stack trace: Crashed: GCDeviceSession.HID 0 libobjc.A.dylib 0x7db8 objc_retain_x8 + 16 1 libsystem_blocks.dylib 0xfb8 void HelperBase<ExtendedInline>::copyCapture<(HelperBase<ExtendedInline>::BlockCaptureKind)3>(unsigned int) + 48 2 libsystem_blocks.dylib 0xbc4 HelperBase<GenericInline>::copyBlock(Block_layout*, Block_layout*) + 108 3 libsystem_blocks.dylib 0xc94 _call_copy_helpers_excp + 60 4 libsystem_blocks.dylib 0xef8 _Block_copy + 412 5 libdispatch.dylib 0x1a70 _dispatch_Block_copy + 32 6 libdispatch.dylib 0x792c dispatch_async + 56 7 libdispatch.dylib 0x792c dispatch_channel_async + 56 8 GameController 0xea6dc -[GCKeyboardInput _handleKeyboardEvent:] + 324 9 GameController 0x22508 __53-[_GCKeyboardEventHIDAdapter initWithSource:service:]_block_invoke + 376 10 GameController 0x11d30 -[_GCHIDEventSubject publishHIDEvent:] + 268 11 GameController 0xb79cc __40-[_GCHIDEventUIKitClient initWithQueue:]_block_invoke_3 + 44 12 libdispatch.dylib 0x1b584 _dispatch_client_callout + 16 13 libdispatch.dylib 0x12088 _dispatch_async_and_wait_invoke_and_complete_recurse + 272 14 libdispatch.dylib 0x8448 _dispatch_async_and_wait_f + 108 15 GameController 0xb7984 __40-[_GCHIDEventUIKitClient initWithQueue:]_block_invoke_2 + 132 16 GameController 0xb746c __48-[__GCHIDEventUIKitClient _initWithApplication:]_block_invoke + 256 17 UIKitCore 0x11fd394 __61-[UIEventFetcher _setHIDGameControllerEventObserver:onQueue:]_block_invoke_3 + 40 18 libdispatch.dylib 0x1aac _dispatch_call_block_and_release + 32 19 libdispatch.dylib 0x1b584 _dispatch_client_callout + 16 20 libdispatch.dylib 0xa2d0 _dispatch_lane_serial_drain + 740 21 libdispatch.dylib 0xadac _dispatch_lane_invoke + 388 22 libdispatch.dylib 0x151dc _dispatch_root_queue_drain_deferred_wlh + 292 23 libdispatch.dylib 0x14a60 _dispatch_workloop_worker_thread + 540 24 libsystem_pthread.dylib 0xa0c _pthread_wqthread + 292 25 libsystem_pthread.dylib 0xaac start_wqthread + 8 Observed scenarios Crash occurs when the app transitions from background to foreground Crash also occurs when the Angular layer requests keyboard status, triggering the same code path Questions Has anyone encountered crashes related to GCKeyboard.coalesced or GCKeyboardInput like this? Are there known issues with the GameController framework when querying keyboard state during app lifecycle transitions? Is there a recommended or safer way to detect external keyboard connection status on iPad (especially when using WKWebView)? Any insights, known platform issues, or suggested workarounds would be greatly appreciated. Thanks!
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561
Activity
Dec ’25
Unity game stutters/lags during rendering on newer iPhone models.
In a Unity game, if the assetBundle.Unloadinterface is called very frequently during normal gameplay, it can cause the game application's screen to freeze, although the background music continues to play normally. This issue only occurs on iPhone 16 and iPhone 17 models, with no problems on lower-version phones. How can this problem be resolved?
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315
Activity
Nov ’25
MPSMatrixRandom SEGFAULTs when ran in an async context
The following minimal snippet SEGFAULTS with SDK 26.0 and 26.1. Won't crash if I remove async from the enclosing function signature - but it's impractical in a real project. import Metal import MetalPerformanceShaders let SEED = UInt64(0x0) typealias T = Float16 /* Why ran in async context? Because global GPU object, and async makeMTLFunction, and async makeMTLComputePipelineState. Nevertheless, can trigger the bug without using global @MainActor let myGPU = MyGPU() */ @main struct CMDLine { static func main() async { let ptr = UnsafeMutablePointer<T>.allocate(capacity: 0) async let future: Void = randomFillOnGPU(ptr, count: 0) print("Main thread is playing around") await future print("Successfully reached the end.") } static func randomFillOnGPU(_ buf: UnsafeMutablePointer<T>, count destbufcount: Int) async { // let (device, queue) = await (myGPU.device, myGPU.commandqueue) let myGPU = MyGPU() let (device, queue) = (myGPU.device, myGPU.commandqueue) // Init MTLBuffer, async let makeFunction, makeComputePipelineState, etc. let tempDataType = MPSDataType.uInt32 let randfiller = MPSMatrixRandomMTGP32(device: device, destinationDataType: tempDataType, seed: Int(bitPattern:UInt(SEED))) print("randomFillOnGPU: successfully created MPSMatrixRandom.") // try await computePipelineState // ^ Crashes before this could return // Or in this minimal case, after randomFillOnGPU() returns // make encoder, set pso, dispatch, commit... } } actor MyGPU { let device : MTLDevice let commandqueue : MTLCommandQueue init() { guard let dev: MTLDevice = MPSGetPreferredDevice(.skipRemovable), let cq = dev.makeCommandQueue(), dev.supportsFamily(.apple6) || dev.supportsFamily(.mac2) else { print("Unable to get Metal Device! Exiting"); exit(EX_UNAVAILABLE) } print("Selected device: \(String(format: "%llX", dev.registryID))") self.device = dev self.commandqueue = cq print("myGPU: initialization complete.") } } See FB20916929. Apparently objc autorelease pool is releasing the wrong address during context switch (across suspension points). I wonder why such obvious case has not been caught before.
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177
Activity
Nov ’25
SwiftCharts to add candlestick and OHLC types to their stable?
I didn't find a suggestion box on Swift's website so I'll post it here. SwiftCharts are great but limited. I need more data on a single chart. Candlestick and OHLC type charts would be an excellent addition. Hopefully, influencers from Apple can make that happen. Thanks.
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3
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266
Activity
Jun ’25
Compute kernel fails to compile when calling texture.read()
If I compile a compute kernel with a call to texture.read(), it fails with the following error: "Error Domain=AGXMetalG13X Code=3 "Encountered unlowered function call to air.get_read_sampler" UserInfo={NSLocalizedDescription=Encountered unlowered function call to air.get_read_sampler}." This error occurs on both macOS and iOS 26 Beta 5, but not when running on a simulator or in a playground. It does not occur on a macOS Sequoia VM. It occurs whether I use the old metal 3 or new metal 4 compilation method. A workaround would be to use a sampler, but according to the feature tables, all platforms support reading from textures of all formats. Below is a minimal example which produces the error: let device = MTLCreateSystemDefaultDevice()! let library = device.makeDefaultLibrary()! let computeFunction = library.makeFunction(name: "compute_test")! do { let pipeline = try device.makeComputePipelineState(function: computeFunction) debugPrint(pipeline) } catch { debugPrint("Metal 3 failed with error:\n\(error)") } #import <metal_stdlib> using namespace metal; kernel void compute_test(uint2 gid [[thread_position_in_grid]], texture2d<float, access::read> in [[texture(0)]], texture2d<float, access::write> out [[texture(1)]]) { out.write(in.read(gid), gid); } I filed feedback FB19530049.
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224
Activity
Aug ’25
Testing Achievements - Apple Documentation out of Date
New to achievements. I added them in App Store Connect and want to test them. Apple Documentation says this: "Before you begin testing your GameKit configuration, you need to enable Debug Mode. In Xcode, choose Product > Scheme > Edit Scheme. From the Run configuration, select Options and toggle Enable Debug Mode. To begin testing your achievement configuration, open the game Progress Manager. In Xcode, choose Debug > GameKit > Manage Game Progress." Sounds easy enough, but there is no "GameKit" under Debug in Xcode 16.2.
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2
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159
Activity
May ’25
Can spatial scene function be used outside of the Photo App?
I'm new here so I don't know what's this function belongs to which topic... Sorry about that! I watched the WWDC stream and I am really interested in this function, I'm wondering if this function could be used in my apps. I looked up the document but I find it only support visionOS(i'm not sure about that, but I saw the demo is base on the visionOS)
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283
Activity
Jun ’25
Customize the Metal Performance HUD on Apple TV
Hi there, Is it possible to customize the Metal Performance HUD on Apple TV, similar to how it can be done on iPhone & iPad? Would like to see things like Compiled Shaders for my Apps on tvOS .
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3
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373
Activity
Aug ’25
Will OpenGL API and Drivers be removed after appleOS 26?
Hi, I am a Multimedia and Graphics researcher and I am wondering if OpenGL API and drivers will be removed after appleOS 26? macOS 26 iOS 26 iPadOS 26 visionOS 26 I am asking this because most of the libraries I use depends on OpenGL. Like CGAL, libigl, immediate mode ui, nanovg, nanogui, bullet physics. Transitioning from Vulkan and metal while using and learning those libraries is just not viable. I would like to ask you that. I am the sole developer and I just want to ask you that. Regards.
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241
Activity
Aug ’25
How to detect which entity was tapped?
Hi, I'm rewriting my game from SceneKit to RealityKit, and I'm having trouble implementing the following scenario: I tap on the iPhone screen to select an Entity that I want to drag. If an Entity was tapped, it should then be possible to drag it left, right, etc. SceneKit solution: func CGPointToSCNVector3(_ view: SCNView, depth: Float, point: CGPoint) -> SCNVector3 { let projectedOrigin = view.projectPoint(SCNVector3Make(0, 0, Float(depth))) let locationWithz = SCNVector3Make(Float(point.x), Float(point.y), Float(projectedOrigin.z)) return view.unprojectPoint(locationWithz) } and then I was calling: SCNView().hitTest(location, options: [SCNHitTestOption.firstFoundOnly:true]) the code was called inside of the UIPanGestureRecognizer in my UIViewController. Could I reuse that code or should I go with the SwiftUI approach - something like that: var body: some View { RealityView { .... } .gesture(TapGesture().onEnded { }) ? I already have this code: @State private var location: CGPoint? .onTapGesture { location in self.location = location } I'm trying to identify the entity that was tapped within the RealityView like that: RealityView { content in let box: ModelEntity = createBox() // for now there is only one box, however there will be many boxes content.add(box) let anchor = AnchorEntity(world: [0, 0, 0]) content.add(anchor) _ = content.subscribe(to: SceneEvents.Update.self) { event in //TODO: find tapped entity, so that it could be dragged inside of the DragGesture() } Any help would be appreciated. I also noticed that if I create a TapGesture like that: TapGesture(count: 1) .targetedToAnyEntity() and add it to my view using .gesture() then it is not triggered.
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297
Activity
Aug ’25
Does OLED burn-in affect iPad Pro displays, and should I implement a screen saver in my always-on app?
Hi everyone, I’m developing an iPad app that will be running continuously with the screen always on — similar to a restaurant ordering system. I understand that some of the newer iPad Pro models are equipped with OLED displays. I'm concerned about the potential risk of screen burn-in due to static UI elements being displayed for extended periods. Does burn-in occur on the OLED iPad Pro models under such usage? Would it be advisable to implement a screen saver or periodically animate/change parts of the UI to prevent this? Any insights or best practices would be greatly appreciated. Thank you!
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143
Activity
Jun ’25
Matchmaking issue on tvOS with GKMatchmakerViewController.Request
Hello ! We are working on a real-time 2-player online game targeting multiple Apple devices. The following issue only occurs on tvOS: When selecting matchmaking to connect with another random player, the native Game Center interface opens and begins the matchmaking process. Almost immediately after clicking "start", the following log appears in the console, and the matchmaking screen remains indefinitely without completing: Timeout while starting matching with request: <GKMatchRequestInternal 0x30d62f690> { defaultNumberOfPlayers : 0 isLateJoin : 0 localPlayerID : U:bea182d69b85f0839e3958742fbc4609 matchType : 0 maxPlayers : 2 minPlayers : 2 playerAttributes : 4294967295 playerGroup : 1 preloadedMatch : 0 recipientPlayerIDs : <__NSArrayM 0x3034ed5c0> {} recipients : <__NSArrayM 0x3034ee280> {} restrictToAutomatch : 0 version : 1 archivedSharePlayInviteeTokensFromProgrammaticInvite, inviteMessage, localizableInviteMessage, messagesBasedRecipients, properties, queueName, recipientProperties, rid, sessionToken : (null) } . Error: (null) However, as shown in the code snippet below, the task does not complete when the log appears. But when we manually cancel the matchmaking process, the "User cancel" log is correctly triggered. var gkMatchRequest = GKMatchRequest.Init(); gkMatchRequest.MinPlayers = 2; gkMatchRequest.MaxPlayers = 2; var matchRequestTask = GKMatchmakerViewController.Request(gkMatchRequest); matchRequestTask.ContinueWith(t => { Debug.LogException(t.Exception); }, TaskContinuationOptions.OnlyOnFaulted); matchRequestTask.ContinueWith(t => { Debug.Log("User cancel"); }, TaskContinuationOptions.OnlyOnCanceled); matchRequestTask.ContinueWith(t => { Debug.Log("Success"); }, TaskContinuationOptions.OnlyOnRanToCompletion); We have tested this on multiple Apple TV and network types (Wi-Fi, 5G, Ethernet), but we consistently encounter this bug along with the same log message. Could you please help us understand or resolve this issue? Thank you.
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254
Activity
Apr ’25