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How can I simultaneously apply the drag gesture to multiple entities?
I wanted to drag EntityA while also dragging EntityB independently. I've tried to separate them by entity but it only recognizes the latest drag gesture RealityView { content, attachments in ... } .gesture( DragGesture() .targetedToEntity(EntityA) .onChanged { value in ... } ) .gesture( DragGesture() .targetedToEntity(EntityB) .onChanged { value in ... } ) also tried using the simultaneously but didn't work too, maybe i'm missing something .gesture( DragGesture() .targetedToEntity(EntityA) .onChanged { value in ... } .simultaneously(with: DragGesture() .targetedToEntity(EntityB) .onChanged { value in ... } )
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709
Mar ’25
Looking for some clarification
Was wondering if anyone from Apple could provide some clarification, The gaming studio "Epic Games" Is wondering if they could distribute the award winning game "Fortnite" back on MacOS without any retaliations. I know Fortnite being back on MacOS would benefit thousands of MacOS Devs. Hoping to get a clarification so Epic could start on bringing Fortnite back.
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611
Dec ’25
PDFKit Page Rerender
I'm experiencing an issue with PDFKit where page.removeAnnotation(annotation) successfully removes the annotation from the page's data structure, but the PDFView no longer updates automatically to reflect the change visually. Issue Details: The annotation is removed (verified by checking page.annotations.count) The PDFView display doesn't refresh to show the removal This code was working correctly before and suddenly stopped working No code changes were made on my end
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825
Dec ’25
Float64 (Double Precision) Support on MPS with PyTorch on Apple Silicon?
Hi everyone, This project uses PyTorch on an Apple Silicon Mac (M1/M2/etc.), and the goal is to use the MPS backend for GPU acceleration, notes Apple Developer. However, the workflow depends on Float64 (double-precision) floating-point numbers for certain computations, notes PyTorch Forums. The error "Cannot convert a MPS Tensor to float64 dtype as the MPS framework doesn't support float64. Please use float32 instead" has been encountered, notes GitHub. It seems that the MPS backend doesn't currently support Float64 for direct GPU computation. Questions for the community: Are there any known workarounds or best practices for handling Float64-dependent operations when using the MPS backend with PyTorch? For those working with high-precision tasks on Apple Silicon, what strategies are being used to balance performance with the need for Float64? Offloading to the CPU is an option, and it's of interest to know if there are any specific techniques or libraries within the Apple ecosystem that could streamline this process while aiming for optimal performance. Any insights, tips, or experiences would be appreciated. Thanks in advance, Jonaid MacBook Pro M3 Max
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447
Oct ’25
Issues building Unity plug-in project: Cannot locate native library Apple.Core/Apple.GameKit for iOS
I'm having issues getting a well built package from the Apple Unity Plug-in project. When building the my game project in Unity the following error is printed to the console: Apple.Core.AppleNativeLibraryUtility] Cannot locate a Debug or Release Apple.Core native library for iOS. Please ensure that the build invocation (build.py, xcodebuild, or Xcode) compiled cleanly and that the build was configured to support Debug on iOS. As far as I can tell the build did compile cleanly, but I might be missing something. If anyone can see what I'm doing wrong or has any insight it would be greatly appreciated. Setup is the following: macOS Tahoe 26 Beta Xcode-beta Version 26.0 beta 3 (17A5276g) Unity Plug-in branch: 2025-beta1 Unity game project version: 2022.3.60f M1 Macbook Pro The built packages have been imported into the game project through the Unity Package Manager using the tarball option pointing to the built packages from the Unity Plug-in project. The Unity Plug-in project has been built using the build.py file with the following: python3 build.py -m iOS iPhoneSimulator -p Core GameKit CoreHaptics GameController -k all The output is available in the attached file. build-output.txt Here's an image of the NativeLibraries~ folder inside the built Apple.Core package.
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1.2k
Oct ’25
visionOS + Unity PolySpatial: Is 15,970 MeshFilters the True Upper Limit for Industrial Scenes?
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)
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728
Oct ’25
The delay issue of 4G TCP connection for iPhone 17 in China's mobile network
Reproduce Same SIM card with 4G, same testing location, connected to the same server, xcode debugging game applications, network/profile retrotransmitted, Avg round trip to view data iPhone17, Turn off 4G and turn on WiFi. All the above indicators are acceptable iPhone17, Turn on 4G, turn off WiFi, retry with retransmission and very high Avg round trip iPhone14-16, Turn on 4G and turn off WiFi. All the above indicators are acceptable App Unity3d project .netframe4.0 C# Socket Other Many developers in Chinese forums have provided feedback on this issue
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772
Oct ’25
Trouble with MDLMesh.newBox()
I'm trying to build an MDLMesh then add normals let mdlMesh = MDLMesh.newBox(withDimensions: SIMD3<Float>(1, 1, 1), segments: SIMD3<UInt32>(2, 2, 2), geometryType: MDLGeometryType.triangles, inwardNormals:false, allocator: allocator) mdlMesh.addNormals(withAttributeNamed: MDLVertexAttributeNormal, creaseThreshold: 0) When I render the mesh, some normals are (0,0,0). I don't know if the problem is in the mesh, or in the conversion to MTKMesh. Is there a way to examine an MDLMesh with the geometry viewer? When I look at the variable values for my mdlMesh I get this: Not too useful. I don't know how to track down the normals. What's the best way to find out where the normals getting broken?
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150
May ’25
RealityKit migration
Hey there, I’m currently planning to use RealityKit in a new multiplatform app I’m building. Unfortunately, I noticed that WatchOS is not supported for RealityKit, while SceneKit is getting deprecated. However, I’d like to maintain the same codebase across platforms. What are my options?
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450
Oct ’25
How can I get pixel coordinates in the fragment tile function?
In this video, tile fragment shading is recommended for image processing. In this example, the unpack function takes two arguments, one of which is RasterizerData. As I understand it, this is the data passed to us from the previous stage (Vertex) of the graphics pipeline. However, the properties of MTLTileRenderPipelineDescriptor do not include an option for specifying a Vertex function. Therefore, in this render pass, a mix of commands is used: first, a draw command is executed to obtain UV coordinates, and then threads are dispatched. My question is: without using a draw command, only dispatch, how can I get pixel coordinates in the fragment tile function? For the kernel tile function, everything is clear. typedef struct { float4 OPTexture [[ color(0) ]]; float4 IntermediateTex [[ color(1) ]]; } FragmentIO; fragment FragmentIO Unpack(RasterizerData in [[ stage_in ]], texture2d<float, access::sample> srcImageTexture [[texture(0)]]) { FragmentIO out; //... // Run necessary per-pixel operations out.OPTexture = // assign computed value; out.IntermediateTex = // assign computed value; return out; }
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181
Mar ’25
Game Center save game data to iCloud
We are trying to implement saving and fetching data to and from iCloud, but it have some problems. MacOS: 15.3 Here is what I do: Enable Game Center and iCloud capbility in Signing & Capabilities, pick iCloud Documents, create and select a Container. Sample code: void SaveDataToCloud( const void* buffer, unsigned int datasize, const char* name ) { if(!GKLocalPlayer.localPlayer.authenticated) return; NSData* data = [ NSData dataWithBytes:databuffer length:datasize]; NSString* filename = [ NSString stringWithUTF8String:name ]; [[GKLocalPlayer localPlayer] saveGameData:data withName:filename completionHandler:^(GKSavedGame * _Nullable savedGame, NSError * _Nullable){ if (error != nil) { NSLog( @"SaveDataToCloud error:%@", [ error localizedDescription ] ); } }]; } void FetchCloudSavedGameData() { if ( !GKLocalPlayer.localPlayer.authenticated ) return; [ [ GKLocalPlayer localPlayer ] fetchSavedGamesWithCompletionHandler:^(NSArray<GKSavedGame *> * _Nullable savedGames, NSError * _Nullable error) { if ( error == nil ) { for ( GKSavedGame *item in savedGames ) { [ item loadDataWithCompletionHandler:^(NSData * _Nullable data, NSError * _Nullable error) { if ( error == nil ) { //handle data } else { NSLog( @"FetchCloudSavedGameData failed to load iCloud file: %@, error:%@", item.name, [ error localizedDescription ] ); } } ]; } } else { NSLog( @"FetchCloudSavedGameData error:%@", [ error localizedDescription ] ); } } ]; } Both saveGameData and fetchSavedGamesWithCompletionHandler are not reporting any error, when debugging, saveGameData completionHandler got a nil error, and can get a valid "savedGame", but when try to rebot the game and use "fetchSavedGamesWithCompletionHandler" to fetch data, we got nothing, no error reported, and the savedGames got a 0 length. From this page https://developer.apple.com/forums/thread/718541?answerId=825596022#825596022 we try to wait 30sec after authenticated , then try fetchSavedGamesWithCompletionHandler, still got the same error. Checked: Game Center and iCloud are enabled and login with the same account. iCloud have enough space to save. So what's wrong with it.
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705
Mar ’25
Metal-CPP Errors
After following the instructions here: https://developer.apple.com/metal/cpp/ I attempted building my project and Xcode presented several errors. In essence it's complaining about some redeclarations in the Metal-CPP headers. NSBundle.hpp and NSError.hpp are included in the metal-cpp/foundation directory from the metal-cpp download. Any help in getting these issues resolved is appreciated. Thanks!
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599
Feb ’25
SceneKit - different behavior when debugging
Hello, I'm currently working on my first SceneKit game and have encountered an issue related to moving an SCNNode using a UIPanGestureRecognizer. When I deploy the game to my iPhone via Xcode in debug mode, all interactions are smooth. However, when I stop the debugging session and run the game directly from the device (outside of Xcode), the SCNNode movement behaves inconsistently — it works sometimes smoothly and sometimes not and the interaction becomes choppy. The SCNNode movement is controlled using a UIPanGestureRecognizer. Do you have any ideas what might be causing the issue?
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247
May ’25
ModelEntity(named:in:) fails to load USD file from RealityKitContent bundle with misleading error?
My experience has been that ModelEntity(named:in:) can be used to load a USD file with a simple structure consisting of entities and model entities, and, critically, it will flatten the entity hierarchy down to a single ModelEntity, presumably reducing the number of draw calls. However, can anyone verify that the following is true? If ModelEntity(named:in:) is used to load a USD file from a RealityKit content bundle, it may fail when the USD file contains more complex data, such as shader graph material definitions, or perhaps for some other reason. I am not sure. AND the error that ModelEntity(named:in:) throws in this case is Cannot load RealityKitContent entity: Failed to find resource with name "<name>" in bundle which would literally suggest that the file does not exist, instead of what I assume the error actually is, which is "the file exists but its entity hierarchy could not be flattened to a single ModelEntity" ? Is that an accurate description of the known behavior of ModelEntity:named:in:)? I understand that I could use Entity(named:in:) instead, without the flattening feature. My question is really more about the seemingly misleading error message. Thank you for any clarification you can provide.
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182
May ’25
Metal calls hanging/stuck if app is started quickly after login
Our app uses Metal for image processing. We have found that if our app (and its possible intensive image processing) is started quickly after user is logged in, then calls to Metal may be hanging/stuck for a good while. Example: it can take 1-2 minutes for something that usually takes 3-5 seconds! Metal threads are just hanging in a memmove... In Activity Monitor we see a lot of things are happening right after log-in. But why Metal calls are blocking for so long is unknown to us... The workaround is to wait a minute before we start our app and start intensive image processing using Metal. But hard to explain this workaround to end-users... It doesn't happen on all computers but fairly easy to reproduce on some computers. We are using macOS 15.3.1. M1/M3 Max. Any good ideas for how to proceed with this problem and possible reach out to Apple engineers? Thanks! :)
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475
Feb ’25
RealityKit VideoMaterial renders pink on iOS 18
our app is live, and it appears that since the ios 18 update - the VideoMaterial renders pink / purple color instead of the video (picture attached). the audio is rendered properly. we found that it occurs on old devices: iPhone 11 & iPhone SE 2020. I've found this thread of Andy Jazz on stackoverflow: Steps to Reproduce: Create a plane for the video screen. Apply a VideoMaterial using AVPlayerItem. Anchor the model entity to an ARImageAnchor. Expected Outcome: The video should play as a material on the plane in RealityKit. Actual Outcome: On iOS 18, the plane appears pink, indicating the VideoMaterial isn’t applied. What I’ve Tried: -Verified the video URL is correct. -Checked that the AVPlayerItem and VideoMaterial are initialised correctly. -Ensured the AVPlayer is playing the video. I also tried different formats (mov / mp4 / m4v), and verifying that the video's status is readyToPlay. any suggestions?
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213
Jun ’25
In Metal compute kernels, when do thread variables get spilled into the device memory?
How many 32-bit variables can I use concurrently in a single thread of a Metal compute kernel without worrying about the variables getting spilled into the device memory? Alternatively: how many 32-bit registers does a single thread have available for itself? Let's say that each thread of my compute kernel needs to store and work with its own array of N float variables, where N can be 128, 256, 512 or more. To achieve maximum possible performance, I do not want to the local thread variables to get spilled into the slow device memory. I want all N variables to be stored "on-chip", in the thread memory space. To make my question more concrete, let's say there is an array thread float localArray[N]. Assuming an unrealistic hypothetical scenario where localArray is the only variable in the whole kernel, what is the maximum value of N for which no portion of localArray would get spilled into the device memory? I searched in the Metal feature set tables, but I could not find any details.
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626
Mar ’25