Render advanced 3D graphics and perform data-parallel computations using graphics processors using Metal.

Metal Documentation

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Unable to package in UE5.6
Im new in the Mac area but for sure not UE. Windows is a long process to packaging but it could be done. All the documentation for Epic and from the internet is basically non existent with exactly how to package a project within UE. I have Xcode installed which makes sense, agreed to terms and install for MacOS, I've been able to make a project for several weeks now and want to package for a test run for my friends to play on Windows. Now I just get this in the log: UATHelper: Packaging (Mac): ERROR: Failed to finalize the .app with Xcode. Check the log for more information UATHelper: Packaging (Mac): Trace written to file /Users/rileysleger/Library/Logs/Unreal Engine/LocalBuildLogs/UBA-ProjectNightTerror-Mac-Development.uba with size 12.6kb UATHelper: Packaging (Mac): Total time in Unreal Build Accelerator local executor: 8.12 seconds UATHelper: Packaging (Mac): Result: Failed (OtherCompilationError) UATHelper: Packaging (Mac): Total execution time: 9.71 seconds PackagingResults: Error: Failed to finalize the .app with Xcode. Check the log for more information UATHelper: Packaging (Mac): Took 9.77s to run dotnet, ExitCode=6 UATHelper: Packaging (Mac): UnrealBuildTool failed. See log for more details. (/Users/rileysleger/Library/Logs/Unreal Engine/LocalBuildLogs/UBA-ProjectNightTerror-Mac-Development.txt) UATHelper: Packaging (Mac): AutomationTool executed for 0h 0m 10s UATHelper: Packaging (Mac): AutomationTool exiting with ExitCode=6 (6) UATHelper: Packaging (Mac): RunUAT ERROR: AutomationTool was unable to run successfully. Exited with code: 6 PackagingResults: Error: AutomationTool was unable to run successfully. Exited with code: 6 PackagingResults: Error: Unknown Error This absolutely makes no sense to me. Anyone have ideas?
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Jul ’25
CustomMetalView sample uses deprecated functions - update?
The sample code here, has code like: // Create a display link capable of being used with all active displays cvReturn = CVDisplayLinkCreateWithActiveCGDisplays(&_displayLink); But that function's doc says it's deprecated and to use NSView/NSWindow/NSScreen displayLink instead. That returns CADisplayLink, not CVDisplayLink. Also the documentation for that displayLink method is completely empty. I'm not sure if I'm supposed to add it to run loop, or what, after I get it. It would be nice to get an updated version of this sample project and/or have some documentation in NSView.displayLink
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Jul ’25
Combining render encoders
When I take a frame capture of my application in Xcode, it shows a warning that reads "Your application created separate command encoders which can be combined into a single encoder. By combining these encoders you may reduce your application's load/store bandwidth usage." In the minimal reproduction case I've identified for this warning, I have two render pipeline states: The first writes to the current drawable, the depth buffer, and a secondary color buffer. The second writes only to the current drawable. Because these are writing to a different set of outputs, I was initially creating two separate render command encoders to handle the draws under each of these states. My understanding is that Xcode is telling me I could only create one, however when I try to do that, I get runtime asserts when attempting to apply the second render pipeline state since it doesn't have a matching attachment configured for the second color buffer or for the depth buffer, so I can't just combine the encoders. Is the only solution here to detect and propagate forward the color/depth attachments from the first state into the creation of the second state? Is there any way to suppress this specific warning in Xcode?
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Jul ’25
CAMetalLayer nextDrawable crash
Hi , My application meet below crash backtrace at very low repro rate from the public users, i do not see it relate to a specific iOS version or iPhone model. The last code line from my application is calling CAMetalLayer nextDrawable API. I did some basic studying, suppose it may relate to the wrong CAMetaLayer configuration, like frame property w or h <= 0.0 bounds property w or h <= 0.0 drawableSize w or h <= 0.0 or w or h > max value (like 16384) Not sure my above thinking is right or not? Will the UIView which my CAMetaLayer attached will cause such nextDrawable crash or not ? Thanks a lot Main Thread - Crashed libsystem_kernel.dylib __pthread_kill libsystem_c.dylib abort libsystem_c.dylib __assert_rtn Metal MTLReportFailure.cold.1 Metal MTLReportFailure Metal _MTLMessageContextEnd Metal -[MTLTextureDescriptorInternal validateWithDevice:] AGXMetalA13 0x245b1a000 + 4522096 QuartzCore allocate_drawable_texture(id<MTLDevice>, __IOSurface*, unsigned int, unsigned int, MTLPixelFormat, unsigned long long, CAMetalLayerRotation, bool, NSString*, unsigned long) QuartzCore get_unused_drawable(_CAMetalLayerPrivate*, CAMetalLayerRotation, bool, bool) QuartzCore CAMetalLayerPrivateNextDrawableLocked(CAMetalLayer*, CAMetalDrawable**, unsigned long*) QuartzCore -[CAMetalLayer nextDrawable] SpaceApp -[MetalRender renderFrame:] MetalRenderer.mm:167 SpaceApp -[FrameBuffer acceptFrame:] VideoRender.mm:173 QuartzCore CA::Display::DisplayLinkItem::dispatch_(CA::SignPost::Interval<(CA::SignPost::CAEventCode)835322056>&) QuartzCore CA::Display::DisplayLink::dispatch_items(unsigned long long, unsigned long long, unsigned long long) QuartzCore CA::Display::DisplayLink::dispatch_deferred_display_links(unsigned int) UIKitCore _UIUpdateSequenceRun UIKitCore schedulerStepScheduledMainSection UIKitCore runloopSourceCallback CoreFoundation __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ CoreFoundation __CFRunLoopDoSource0 CoreFoundation __CFRunLoopDoSources0 CoreFoundation __CFRunLoopRun CoreFoundation CFRunLoopRunSpecific GraphicsServices GSEventRunModal UIKitCore -[UIApplication _run] UIKitCore UIApplicationMain
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Jul ’25
Problem running Unreal 5.6
I am using Unreal Engine 5.6 on a MacBook Pro with an M3 chip and macOS 15.5. I’ve installed Xcode and accepted the license, but Unreal is not detecting the latest Metal Shader Standard (Metal v3.0). The maximum version Unreal sees is Metal v2.4, even though the hardware and OS should support Metal 3.0. I’ve also run sudo xcode-select -s /Applications/Xcode.app and accepted the license via Terminal. Is there anything in Xcode settings, SDK availability, or system permissions that could be preventing access to Metal 3.0 features?"
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Jul ’25
Background GPU Access availability
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!
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1k
Jul ’25
Metal IR reference
Hello! I'm developing a GPU (shader) language, where I aim to target multiple backends with a common frontend. I wanted to avoid having to round trip through Metal, and go straight to IR just like I have with SPIRV, in order to have a fast and efficient compilation process. I've been looking for a reference page where I can read about Metals IR, and as far as I'm aware, it exists, but I can't seem to find it anywhere. Furthermore, if such a reference is available, is there also a toolkit where I can run validation on the output IR, and perhaps even run optimizations, much like spv-tools for SPIRV? Any help would be appreciated! Thanks, Gustav
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Jul ’25
Warning code: 00000006 will affect background survival
Our APP has integrated 3D function, in order to reduce the memory occupation of the APP in the background, we will uninstall the 3D after the APP enters the background. However, the uninstall also causes problems. When the uninstall process is executed in the background, the app will briefly trigger the background GPU rendering error warning with the error warning code: OGPUMetalError: Insufficient Permission (to submit GPU work from background) (00000006:kIOGPUCommandBufferCallbackErrorBackgroundExecutionNotPermitted) Execution of the command buffer was aborted due to an error during execution. Insufficient Permission (to submit GPU Work from background) (00000006: kIOGPUCommandBufferCallbackErrorBackgroundExecutionNotPermitted) excuse me this warning system will tighten APP permissions background?​ For example, limit or shorten the background survival time of the APP. In addition, will the background refresh function fail, resulting in the failure of Bluetooth Ibeacon activation?
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Aug ’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
Metal HUD Display Value Range
Can't seem to get the Metal HUD to display value range's (pre 26 Tahoe). The documented environment variable MTL_HUD_SHOW_VALUE_RANGE doesn't seem to work. https://developer.apple.com/documentation/xcode/monitoring-your-metal-apps-graphics-performance#Display-the-value-range-of-metrics Anyone having any luck?
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Sep ’25
Metal fails to create PSO on AMD based GPUs
Hello, Shaders in our application is written using HLSL and we rely on Metal Shader Converter to convert DXIL to Metal IR. We ran into an issue that causes metal pipeline state creation to fail when vertex stage-in function is used on AMD GPUs. Here's the error reported by Metal in Xcode output: Compiler failed with XPC_ERROR_CONNECTION_INTERRUPTED XPC_ERROR_CONNECTION_INTERRUPTED MTLCompiler: Compilation failed with XPC_ERROR_CONNECTION_INTERRUPTED on 4 try. This error suggests an unexpected interruption in the connection. Possible reasons: a crash in the compiler service, termination by the OS due to resource constraints (e.g., jetsam), a timeout in the service, or an issue with IPC. Verify system stability and check the logs for more details. Compiler failed with XPC_ERROR_CONNECTION_INVALID XPC_ERROR_CONNECTION_INVALID MTLCompiler: Compiler encountered XPC_ERROR_CONNECTION_INVALID: failed to check-in, peer may have been unloaded: mach_error=10000003 (is the OS shutting down or process jetsammed?) Compilation failed due to an interrupted connection: XPC_ERROR_CONNECTION_INTERRUPTED. This error occurred after multiple retries. which seems to indicate a internal compiler error. I have a minimal repro here: https://github.com/kcloudy0717/metal_pso_fail/tree/main, simply follow the instructions in README.
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Sep ’25
Pink screen on MTLCommandBuffer.presentDrawable.
I rewrote my graphics pipeline to use Load/Store better for clearing and don't care cases. All my tests pass, and in the Metal debugger, all the draw calls succeed. But when I present drawables (before [commandBuffer commit]) I only get a pink screen. I've tried everything I can think of: making sure the pixel formats are the same for the back buffer as my render targets, etc. But it's still pink. Could you point me in the right direction so I can fix this, or help describe why it's pink. That would be really helpful. Thank you, Brian Hapgood
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411
Sep ’25
10-bit support in iPad Pro
Hi, I’m using the latest iPad Pro (13-inch) and I can see that Metal offers an rgb10a2unorm texture for rendering, but when I render a grey ramp and measure the actual luminance, I get a pattern that I would expect from an 8-bit texture (see below). Before I start ripping apart all my code, is there anything else I need to do to convince iOS to render my texture in 10-bit? I already tried setting the PixelFormat in my CMetalLayer to rgb10a2unorm, but that didn’t change anything.
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Sep ’25
Can you delete a MTLLibrary once shaders are placed into pipeline?
Hello, I am quite new to using the metal API and was wondering if it was common (or even possible) if you knew that, when a pipeline was created, you never needed to make another one with the same shaders again, if it is safe to release the library the was used to reference the shaders? Only asking because this is possible in other apis, but apple never mentions (as far as I have found) if this is safe or not safe to do.
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Oct ’25
NSScreen's maximumExtendedDynamicRangeColorComponentValue does not seem to provide the proper value after sleep/wake on third party HDR displays even when there is EDR content on screen in macOS Tahoe
The maximumExtendedDynamicRangeColorComponentValue should provide some value between 1.0 and maximumPotentialExtendedDynamicRangeColorComponentValue depending on the available EDR headroom if there is any content on-screen that uses EDR. This works fine in most scenarios but in macOS 26 Tahoe (including in 26.2) this seemingly breaks down when a third party external display is in HDR mode and the Mac goes to sleep and wakes up. After wake only a value of 1.0 is provided by the third party external display's NSScreen object, no matter what (although when the SDR peak brightness is being changed using the brightness slider, didChangeScreenParametersNotification is firing and the system should provide a proper updated headroom value). This makes dynamic tone-mapping that adapts to actual screen brightness impossible. Everything works fine in Sequoia. In Tahoe the user needs to turn off HDR, then go through a sleep/wake cycle and turn HDR back on to have this fixed, which is obviously not a sustainable workaround.
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Dec ’25
Metal 4: Proper usage of requestResidency() with unique per-frame textures at 120fps
Hello, I have some confusion regarding ResidencySet. Specifically, about the requestResidency() function: how often should we call it? I have a captureOutput(_:didOutput:from:) method that is triggered at 60 or 120 fps. Inside this method, I am calling the following code every frame: computeResidencySet.removeAllAllocations() сomputeResidencySet.addAllocation(TextureA) computeResidencySet.addAllocation(TextureB) computeResidencySet.addAllocation(TextureC) computeResidencySet.commit() computeResidencySet.requestResidency() // Should we call it every frame? Please keep in mind that TextureA, TextureB, and TextureC are unique for each call (new instances are provided on every frame)."
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605
Jan ’26
MTLBinaryArchive Size
I'm trying to use MTLBinaryArchive. I collected a BinaryArchive from one device and used metal-tt to translate it for all supported iPhone devices, ranging from iPhone 7 Plus to iPhone 16. However, this BinaryArchive is quite large, around 1.5GB uncompressed, and about 500MB compressed in the IPA. I'm wondering how to address the size issue. I watched the WWDC 2022 video, which mentioned that the operating system or app installation process would handle compatibility. Does this compatibility support different GPU chips? I tried installing an IPA with a BinaryArchive collected only from an iPhone 12 on an iPhone 13, but the BinaryArchive didn't take effect. I also saw that Apple supports App Thinning. However, it seems that resources in the Asset Catalog cannot be accessed via URL, and creating an MTLBinaryArchive requires a URL. Is it possible for MTLBinaryArchive to be distributed through App Thinning? The WWDC 2022 video also mentioned using the -Os optimization flag to reduce size. Can this give an estimate of how much compression it would achieve? Are there any methods to solve the BinaryArchive size issue without impacting performance?
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Mar ’25
Slow compilation
Hi, I am working with a large project. We are compiling each material to its own .metallib. They all include many common files full of inline functions. Finally we link it all together at the end with a single big pathtrace kernel. Everything works as expected, however the compile times have gotten completely out of hand and it takes multiple minutes to compile at runtime (to native code). I have gathered that I can do this offline by using metal-tt however if I am wondering if there is a way to reduce the compile times in such a scenario, and how to investigate what the root cause of the problem is. I suspect it could have to do with the fact that every materials metallib contains duplications of all the inline functions. Any ideas on how to profile and debug this? Thanks, Rasmus
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Mar ’25