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Subject: Handling Z-Up Blender USDZ Models in RealityKit (visionOS) for Transform Updates
Hello everyone, I'm working on a visionOS application using RealityKit and am encountering a common coordinate system challenge when integrating 3D models created in Blender. My goal is to display and dynamically update the Transform (position, rotation, scale) of models created in Blender within RealityKit. The issue arises because Blender's default coordinate system is Z-up, and while exporting to USD/USDZ, I don't have a reliable "Y-up" export option that correctly reorients the model and its transform data for RealityKit's Y-up convention. This means I'm essentially exporting models with their "up" direction along the Z-axis. When I load these Z-up exported models into RealityKit, they are often oriented incorrectly. To then programmatically update their Transform (e.g., move them, rotate them based on game logic, or apply physics), I need to ensure that the Transform values I set align with RealityKit's Y-up system, even though the original model data was authored in a Z-up context. My questions are: What is the recommended transformation process (e.g., using simd_quatf or simd_float4x4) to convert a Transform that was conceptually defined in a Z-up coordinate system to RealityKit's Y-up coordinate system? Specifically, when I have a Transform (or its translation, rotation, scale components) from a Z-up context, how should I apply this to a RealityKit Entity so it appears and behaves correctly in a Y-up world? Are there any existing convenience APIs or helper functions within RealityKit, simd, or other Apple frameworks that simplify this Z-up to Y-up Transform conversion process? Or is a manual application of a transformation quaternion (e.g., simd_quatf(angle: -.pi / 2, axis: [1, 0, 0])) the standard approach? Any guidance, code examples, or best practices from those who have faced similar challenges would be greatly appreciated! Thank you.
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493
Jul ’25
Why does game mode not get triggered for my App?
I think I really have tried everything and I did all according to official documentation to support game mode on iOS or iPadOS but it doesn't matter what I do it just doesn't get triggered. Funny enough it works during development when I install it via Xcode but as soon as it is live on the store and when I install it from there game mode doesn't get triggered anymore. What I have atm I have added (even though it is deprecated) <key>GCSupportsGameMode</key> <true/> I have set the (but it seems only supported for macOS) <key>LSApplicationCategoryType</key> <string>public.app-category.games</string> I have added <key>LSSupportsGameMode</key> <true/> It just doesn't work. Is there anything else what needs to be done? Should the flag LSSupportsGameMode not be enough normally? The reason why this is so annoying is that my app is a real time streaming app and I want to profit from minimised background activities for smoother gameplay and more consistent frame rates like mentioned in the documentation.
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743
Nov ’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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395
Apr ’25
How to Configure angularLimitInYZ for PhysicsSphericalJoint in RealityKit (Pendulum/Swing Behavior)
Hello RealityKit developers, I'm currently working on physics simulations in my visionOS app and am trying to adapt the concepts from the official sample Simulating physics joints in your RealityKit app. In the sample, a sphere is connected to the ceiling using a PhysicsRevoluteJoint to create a hinge-like simulation. I've successfully modified this setup to use a PhysicsSphericalJoint instead. The basic replacement works as expected: pin1 (attached to the sphere) rotates freely around pin0 (attached to the ceiling), much like a ball-and-socket joint should, removing all translational degrees of freedom. My challenge lies with the PhysicsSphericalJoint's angularLimitInYZ property. The documentation mentions that this property allows limiting the rotation around the Y and Z axes, defining an "elliptical cone shape around the x-axis of pin0." However, I'm struggling to understand how to specify these values to achieve a desired rotational limit. If I have a sphere that is currently capable of rotating 360 degrees around pin0 (like a free-spinning ball on a string), how would I use angularLimitInYZ to restrict its rotation to a certain height or angular range, preventing it from completing a full circle? Specifically, I'm trying to achieve a "swing" like behavior where the sphere oscillates back and forth but cannot rotate completely overhead or underfoot. What values or approach should I use for the angularLimitInYZ tuple to define such a restricted pendulum-like motion? Any insights, code examples, or explanations on how to properly configure angularLimitInYZ for this kind of behavior would be incredibly helpful! The following code is modified from the sample. extension MainView { func addPinsTo(ballEntity: Entity, attachmentEntity: Entity) throws { let hingeOrientation = simd_quatf(from: [1, 0, 0], to: [0, 0, 1]) let attachmentPin = attachmentEntity.pins.set( named: "attachment_hinge", position: .zero, orientation: hingeOrientation ) let relativeJointLocation = attachmentEntity.position( relativeTo: ballEntity ) let ballPin = ballEntity.pins.set( named: "ball_hinge", position: relativeJointLocation, orientation: hingeOrientation ) // Create a PhysicsSphericalJoint between the two pins. let revoluteJoint = PhysicsSphericalJoint(pin0: attachmentPin, pin1: ballPin) try revoluteJoint.addToSimulation() } } The following image is a screenshot of the operation when changing to PhysicsSphericalJoint. Thank you in advance for your assistance.
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278
Jul ’25
RealityKit and Reality Composer Pro aren't forward or backward compatible with each other
TL;DR: RealityKit and Reality Composer Pro aren't forward or backward compatible with each other, and the resulting error message is terse and unhelpful. (FB14828873) So far, I've been sticking with Xcode 16.4 for development and only using Xcode 26.0 beta experimentally. Yesterday, I used xcode-select to switch to Xcode 26.0 beta 3 to test it, but I forgot to switch back. Consequently, this morning I unintentionally used the future Reality Composer Pro (the version included with Xcode 26) to make a small change to a USD file. Now I realize that if I'm unlucky, it's possible Reality Composer Pro may have silently introduced a small change into the USD file that may make RealityKit fail to read the file on iOS 18 and visionOS 2, which in the past has resulted in hours of debugging to track down the source of the failure, often a single line in the USD file that RealityKit can't communicate to me other than with the error "the operation couldn't be completed". As an analogy, this situation is as if, during regular development (not involving Reality Composer Pro), Xcode didn't warn you about specific API version conflicts, but instead failed with a generic error message, without highlighting the line in your Swift file that was the source of the error.
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476
Jul ’25
Question on setVertexBytes
I think if your buffer is less than 4k its recommended to use setVertexBytes, the question I have is can I keep hammering on setVertexBytes as the primary method to issue multiple draw calls within a render buffer and rely on Metal to figure out how to orphan and replace the target buffer? A lot of the primitives I am drawing are less than 4k and the process of wiring down larger segments of memory for individual buffers for each draw primitive call seems to be a negative. And it's just simpler to copy, submit and forget about buffer synchronization.
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466
3w
Unity GameKit Plugin w/ Matchmaking Queue is not working
TLDR; I can't get QueueName to work with matchmaking a turn-based match in Unity using matchmaking rules. Long version: I'm using the apple unity plugin found here: https://github.com/apple/unityplugins/blob/main/plug-ins/Apple.GameKit/Apple.GameKit_Unity/Assets/Apple.GameKit/Documentation~/Apple.GameKit.md I have created a Queue, RuleSet and a simple Rule to match players by following these docs tightly: https://developer.apple.com/documentation/gamekit/finding-players-using-matchmaking-rules. Here is the single rule I have that drives matchmaking: { "data" : { "type" : "gameCenterMatchmakingRules", "id" : "[hiddden-rule-id]", "attributes" : { "referenceName" : "ComplimentaryFactionPreference", "description" : "default desc", "type" : "MATCH", "expression" : "requests[0].properties.preference != requests[1].properties.preference", "weight" : null }, "links" : { "self" : "https://api.appstoreconnect.apple.com/v1/gameCenterMatchmakingRules/[hidden-rule-id]" } }, "links" : { "self" : "https://api.appstoreconnect.apple.com/v1/gameCenterMatchmakingRules" } } which belongs to a rule set which belongs to a queue. I have verified these are setup and linked via the App Store Connect API. Additionally, when I tested queue-based matchmaking without a queue established, I got an error in Unity. Now, with this, I do not. However there is a problem when I attempt to use the queue for matchmaking. I have the basic C# function here: public override void StartSearch(NSMutableDictionary<NSString, NSObject> properties) { if (searching) return; base.StartSearch(properties); //Establish matchmaking requests _matchRequest = GKMatchRequest.Init(); _matchRequest.QueueName = _PreferencesToQueue(GetSerializedPreferences()); _matchRequest.Properties = properties; _matchRequest.MaxPlayers = PLAYERS_COUNT; _matchRequest.MinPlayers = PLAYERS_COUNT; _matchTask = GKTurnBasedMatch.Find(_matchRequest); } The _PreferencesToQueue(GetSerializedPreferences()); returns the exact name of the queue I added my ruleset to. After this function is called, I poll the task generated from the .Find(...) function. Every time I run this function, a new match is created almost instantly. No two players are ever added to the same match. Further, I'm running two built game instances, one on a mac and another on an ipad and when I simultaneously test, I am unable to join games this way. Can someone help me debug why I cannot seem to match make when using a queue based approach?
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1k
Sep ’25
How to verify with the appropriate signing authority that Apple signed the public key
Hello I trying to implement authentication via apple services in unity game with server made as another unity app On client side I succesfully got teamPlayerID signature salt timestamp publicKeyUrl According to this documentation https://developer.apple.com/documentation/gamekit/gklocalplayer/fetchitems(foridentityverificationsignature:)?language=objc I have to Verify with the appropriate signing authority that Apple signed the public key. As I said my server is special build of unity project So now I have this kind of C# programm to check apple authority over public certificate i got from publicKeyUrl TextAsset textAsset; byte[] bytes; textAsset = Resources.Load&lt;TextAsset&gt;("AppleRootCA-G3"); bytes = textAsset.bytes; rootCert.ChainPolicy.ExtraStore.Add(new X509Certificate2(bytes)); textAsset = Resources.Load&lt;TextAsset&gt;("AppleRootCA-G2"); bytes = textAsset.bytes; rootCert.ChainPolicy.ExtraStore.Add(new X509Certificate2(bytes)); textAsset = Resources.Load&lt;TextAsset&gt;("AppleIncRootCertificate"); bytes = textAsset.bytes; rootCert.ChainPolicy.ExtraStore.Add(new X509Certificate2(bytes)); rootCert.Build(cert); Where cert is X509Certificate2 object I ge from publicKeyUrl AppleIncRootCertificate AppleRootCA-G2 AppleRootCA-G3 is certificates I got from https://www.apple.com/certificateauthority/ But it is not work Anytime rootCert.Build(cert); return false Why it is not work? May be I build keychain using wrong root CA cert? Or whole approach incorrect? Please help
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158
Jun ’25
RealityKit not behaving as expected
This week, I developed a small multiplatform RealityKit project. I also created a demo scene in Reality Composer Pro. Afterward, I imported the local package into the project. Running the project on macOS works perfectly. However, when I tried to run it on my iPhone, I encountered a permission error indicating that it couldn’t read the package. This seems unusual to me because I assumed that the dependency is bundled into the binary file. In an attempt to resolve the issue, I pushed the RCP package to GitHub, hoping it would work. Fortunately, everything compiles successfully now, but the loading time is significantly long, and the animations don’t play on tap gestures. Could someone please help me identify the root cause of this problem?
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355
Jul ’25
GameKit Configuration File - Apple Documentation out of Date
This is the first time I have tried adding achievements to my games. The online documentation says: "Before you can access achievements in your code, you can configure them in Xcode and sync the configuration updates you make with App Store Connect. Begin configuring achievements by creating a GameKit configuration file. In Xcode, choose File > New > File from Template. Select GameKit File, and click Next. In the sheet that appears, enter a name for the configuration and click Create." Sounds easy - except Xcode 16.2 does not have a GameKit File as one of the Templates. Please advise on how to proceed and it would be nice if the documentation were updated.
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153
May ’25
PhotogrammetrySession fails with internal errors 4011 / 4012 when using iOS Object Capture (Area Mode) images
Hi all, I’m running into an issue when trying to reconstruct a 3D model using PhotogrammetrySession on macOS from a set of images captured via the iOS Object Capture sample app, specifically in Area mode. When I attempt to create the model from these images (using the raw Images/ folder exported directly from the capture session), I get the following errors: ERROR cv3dapi.pg: Internal error codes (2): 4011 4012 WARN cv3dapi.pg: Internal warning codes (1): 4507 Output error with code = -15 requestError: CoreOC.PhotogrammetrySession.Error.processError I use the "Images" directory directly exported from Object Capture with my iphone 12 pro max (has lidar) set to "area mode" in the object capture app here is an example heic image metadata from the sequence. heif-info Images/00044.869568833.HEIC MIME type: image/heic main brand: heic compatible brands: mif1, MiHE, MiPr, miaf, MiHB, heic image: 3024x4032 (id=49), primary tiles: 6x8, tile size: 512x512 colorspace: YCbCr, 4:2:0 bit depth: 8 thumbnail: 240x320 color profile: nclx alpha channel: no depth channel: yes size: 192x256 bits per pixel: 8 z-near: 1.173828 z-far: 2.552734 d-min: undefined d-max: undefined representation: uniform Z metadata: Exif: 960 bytes uri /tag:apple.com,2023:ObjectCapture#CameraTrackingState: 4 bytes uri /tag:apple.com,2023:ObjectCapture#CameraCalibrationData: 1015 bytes uri /tag:apple.com,2023:ObjectCapture#ObjectTransform: 48 bytes uri /tag:apple.com,2023:ObjectCapture#ObjectBoundingBox: 48 bytes uri /tag:apple.com,2023:ObjectCapture#RawFeaturePoints: 832 bytes uri /tag:apple.com,2023:ObjectCapture#PointCloudData: 23984 bytes uri /tag:apple.com,2023:ObjectCapture#BundleVersion: 5 bytes uri /tag:apple.com,2023:ObjectCapture#SegmentID: 4 bytes uri /tag:apple.com,2024:ObjectCapture#SessionUUID: 36 bytes uri /tag:apple.com,2024:ObjectCapture#CaptureMode: 4 bytes uri /tag:apple.com,2023:ObjectCapture#Feedback: 4 bytes uri /tag:apple.com,2023:ObjectCapture#WideToDepthCameraTransform: 48 bytes uri /tag:apple.com,2023:ObjectCapture#TemporalDepthPointClouds: 864026 bytes transformations: angle (ccw): 270 region annotations: none properties: camera intrinsic matrix: focal length: 2813.695557; 2813.695557 principal point: 1522.338502; 2002.843018 skew: 0.000000 camera extrinsic matrix: rotation matrix: -0.695 0.344 -0.632 0.007 -0.875 -0.483 -0.719 -0.340 0.606 Questions: • What do internal error codes 4011 and 4012 refer to? • Is there something specific about Area mode captures that require preprocessing before they’re compatible with PhotogrammetrySession? • Has anyone successfully reconstructed a model from an Area mode session using the stock Apple tools? NOTE: I can provide the folder of images for debugging if that would help!
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1k
Jul ’25
How to customize shader code for visionos ?
Hello experts, I'm trying to implement a material with custom shader code, but I saw that visionOS doesn't allow you to inject custom Metal functions or use CustomMaterial like iOS/macOS, nor can you directly write Metal Shading Language (.metal) and use it through ShaderGraphMaterial. So my question is, if i want to implement your own shader code, how should i do it?
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518
Jul ’25
SKScene editor canvas gone
I've recently run into an issue in Xcode where the sks editor's preview canvas just vanishes for every project on my computer. I don't think it is an issue with my sks files because this works as expected on another computer with the same files, and when it happens it happens for ALL sks files in all projects. There used to be menu items to toggle the canvas and its settings, but those are now gone for me in sks files (they show up for swift files that have previews, however). Any idea what is going on here? How do I get the canvas back? I literally cannot get any work done on my primary computer because of this...
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666
Dec ’25
iPhone Pro Model - RefreshRate
I want to display the refresh rate on the screen of the iPhone (14 Pro Max), but each app of the App Store's "Floating Clock", "Floating Clock Premium" and "Screen Renewal Rate - RefreshRate Realtime" can only display two of 60Hz and 120Hz, and I wonder if it can display numbers of 1Hz, 10Hz, tens of Hz, or more than 3 levels. Does anyone know how to do it?
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329
Sep ’25
Custom GCController subclass for new hardware?
Hi all, Wondering how I would go about creating a plugin/class to support a new (physical/hardware) device with the game controller framework? Between GCVirtualController on iOS and the "KeyboardAndMouseSupport.bundle" I see inside GameController.framework on my Mac, it looks like the framework must be designed to support this but I can't find any documentation. Thanks!
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966
Jan ’26
Game Center fetchSavedGames sometimes returns empty list of games, although it works correctly on the next tries
I have implemented the Game Center for authentication and saving player's game data. Both authentication and saving player's data works correctly all the time, but there is a problem with fetching and loading the data. The game works like this: At the startup, I start the authentication After the player successfully logs in, I start loading the player's data by calling fetchSavedGames method If a game data exists for the player, I receive a list of SavedGame object containing the player's data The problem is that after I uninstall the game and install it again, sometimes the SavedGame list is empty(step 3). But if I don't uninstall the game and reopen the game, this process works fine. Here's the complete code of Game Center implementation: class GameCenterHandler { public func signIn() { GKLocalPlayer.local.authenticateHandler = { viewController, error in if let viewController = viewController { viewController.present(viewController, animated: false) return } if error != nil { // Player could not be authenticated. // Disable Game Center in the game. return } // Auth successfull self.load(filename: "TestFileName") } } public func save(filename: String, data: String) { if GKLocalPlayer.local.isAuthenticated { GKLocalPlayer.local.saveGameData(Data(data.utf8), withName: filename) { savedGame, error in if savedGame != nil { // Data saved successfully } if error != nil { // Error in saving game data! } } } else { // Error in saving game data! User is not authenticated" } } public func load(filename: String) { if GKLocalPlayer.local.isAuthenticated { GKLocalPlayer.local.fetchSavedGames { games, error in if let game = games?.first(where: {$0.name == filename}){ game.loadData { data, error in if data != nil { // Data loaded successfully } if error != nil { // Error in loading game data! } } } else { // Error in loading game data! Filename not found } } } else { // Error in loading game data! User is not authenticated } } } I have also added Game Center and iCloud capabilities in xcode. Also in the iCloud section, I selected the iCloud Documents and added a container. I found a simillar question here but it doesn't make things clearer.
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1.2k
Dec ’25
Monthly recurring leaderboard and placement achievement?
I would like a monthly recurring leaderboard, but the most days one can set for the recurring leaderboard is 30, and some months have 31 days (or 28/29). This is dumb. I guess I have to manually reset a classic leaderboard each month to get this result? Additionally once it closes and is about to reset (I also have daily recurring leaderboards), I'd like to grant the top placers on the leaderboard a corresponding achievement, but I don't see any way of doing this. I believe I can do all these things on PlayFab, but it'll take a bit more work, and eventually cost. Any one have advise?
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207
Sep ’25
Gamekit Achievements Won't Unhide
Added achievements to my approved app. Added them for the next release version, which I am running in simulator. When I look at the Achievements page, I can see that there are 17 Achievements available (correct), but they all show as hidden, despite checking the "No" box in App Store Connect.
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162
May ’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
Apr ’25
Subject: Handling Z-Up Blender USDZ Models in RealityKit (visionOS) for Transform Updates
Hello everyone, I'm working on a visionOS application using RealityKit and am encountering a common coordinate system challenge when integrating 3D models created in Blender. My goal is to display and dynamically update the Transform (position, rotation, scale) of models created in Blender within RealityKit. The issue arises because Blender's default coordinate system is Z-up, and while exporting to USD/USDZ, I don't have a reliable "Y-up" export option that correctly reorients the model and its transform data for RealityKit's Y-up convention. This means I'm essentially exporting models with their "up" direction along the Z-axis. When I load these Z-up exported models into RealityKit, they are often oriented incorrectly. To then programmatically update their Transform (e.g., move them, rotate them based on game logic, or apply physics), I need to ensure that the Transform values I set align with RealityKit's Y-up system, even though the original model data was authored in a Z-up context. My questions are: What is the recommended transformation process (e.g., using simd_quatf or simd_float4x4) to convert a Transform that was conceptually defined in a Z-up coordinate system to RealityKit's Y-up coordinate system? Specifically, when I have a Transform (or its translation, rotation, scale components) from a Z-up context, how should I apply this to a RealityKit Entity so it appears and behaves correctly in a Y-up world? Are there any existing convenience APIs or helper functions within RealityKit, simd, or other Apple frameworks that simplify this Z-up to Y-up Transform conversion process? Or is a manual application of a transformation quaternion (e.g., simd_quatf(angle: -.pi / 2, axis: [1, 0, 0])) the standard approach? Any guidance, code examples, or best practices from those who have faced similar challenges would be greatly appreciated! Thank you.
Replies
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493
Activity
Jul ’25
Why does game mode not get triggered for my App?
I think I really have tried everything and I did all according to official documentation to support game mode on iOS or iPadOS but it doesn't matter what I do it just doesn't get triggered. Funny enough it works during development when I install it via Xcode but as soon as it is live on the store and when I install it from there game mode doesn't get triggered anymore. What I have atm I have added (even though it is deprecated) <key>GCSupportsGameMode</key> <true/> I have set the (but it seems only supported for macOS) <key>LSApplicationCategoryType</key> <string>public.app-category.games</string> I have added <key>LSSupportsGameMode</key> <true/> It just doesn't work. Is there anything else what needs to be done? Should the flag LSSupportsGameMode not be enough normally? The reason why this is so annoying is that my app is a real time streaming app and I want to profit from minimised background activities for smoother gameplay and more consistent frame rates like mentioned in the documentation.
Replies
1
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0
Views
743
Activity
Nov ’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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1
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395
Activity
Apr ’25
How to Configure angularLimitInYZ for PhysicsSphericalJoint in RealityKit (Pendulum/Swing Behavior)
Hello RealityKit developers, I'm currently working on physics simulations in my visionOS app and am trying to adapt the concepts from the official sample Simulating physics joints in your RealityKit app. In the sample, a sphere is connected to the ceiling using a PhysicsRevoluteJoint to create a hinge-like simulation. I've successfully modified this setup to use a PhysicsSphericalJoint instead. The basic replacement works as expected: pin1 (attached to the sphere) rotates freely around pin0 (attached to the ceiling), much like a ball-and-socket joint should, removing all translational degrees of freedom. My challenge lies with the PhysicsSphericalJoint's angularLimitInYZ property. The documentation mentions that this property allows limiting the rotation around the Y and Z axes, defining an "elliptical cone shape around the x-axis of pin0." However, I'm struggling to understand how to specify these values to achieve a desired rotational limit. If I have a sphere that is currently capable of rotating 360 degrees around pin0 (like a free-spinning ball on a string), how would I use angularLimitInYZ to restrict its rotation to a certain height or angular range, preventing it from completing a full circle? Specifically, I'm trying to achieve a "swing" like behavior where the sphere oscillates back and forth but cannot rotate completely overhead or underfoot. What values or approach should I use for the angularLimitInYZ tuple to define such a restricted pendulum-like motion? Any insights, code examples, or explanations on how to properly configure angularLimitInYZ for this kind of behavior would be incredibly helpful! The following code is modified from the sample. extension MainView { func addPinsTo(ballEntity: Entity, attachmentEntity: Entity) throws { let hingeOrientation = simd_quatf(from: [1, 0, 0], to: [0, 0, 1]) let attachmentPin = attachmentEntity.pins.set( named: "attachment_hinge", position: .zero, orientation: hingeOrientation ) let relativeJointLocation = attachmentEntity.position( relativeTo: ballEntity ) let ballPin = ballEntity.pins.set( named: "ball_hinge", position: relativeJointLocation, orientation: hingeOrientation ) // Create a PhysicsSphericalJoint between the two pins. let revoluteJoint = PhysicsSphericalJoint(pin0: attachmentPin, pin1: ballPin) try revoluteJoint.addToSimulation() } } The following image is a screenshot of the operation when changing to PhysicsSphericalJoint. Thank you in advance for your assistance.
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278
Activity
Jul ’25
RealityKit and Reality Composer Pro aren't forward or backward compatible with each other
TL;DR: RealityKit and Reality Composer Pro aren't forward or backward compatible with each other, and the resulting error message is terse and unhelpful. (FB14828873) So far, I've been sticking with Xcode 16.4 for development and only using Xcode 26.0 beta experimentally. Yesterday, I used xcode-select to switch to Xcode 26.0 beta 3 to test it, but I forgot to switch back. Consequently, this morning I unintentionally used the future Reality Composer Pro (the version included with Xcode 26) to make a small change to a USD file. Now I realize that if I'm unlucky, it's possible Reality Composer Pro may have silently introduced a small change into the USD file that may make RealityKit fail to read the file on iOS 18 and visionOS 2, which in the past has resulted in hours of debugging to track down the source of the failure, often a single line in the USD file that RealityKit can't communicate to me other than with the error "the operation couldn't be completed". As an analogy, this situation is as if, during regular development (not involving Reality Composer Pro), Xcode didn't warn you about specific API version conflicts, but instead failed with a generic error message, without highlighting the line in your Swift file that was the source of the error.
Replies
1
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0
Views
476
Activity
Jul ’25
Question on setVertexBytes
I think if your buffer is less than 4k its recommended to use setVertexBytes, the question I have is can I keep hammering on setVertexBytes as the primary method to issue multiple draw calls within a render buffer and rely on Metal to figure out how to orphan and replace the target buffer? A lot of the primitives I am drawing are less than 4k and the process of wiring down larger segments of memory for individual buffers for each draw primitive call seems to be a negative. And it's just simpler to copy, submit and forget about buffer synchronization.
Replies
1
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0
Views
466
Activity
3w
Unity GameKit Plugin w/ Matchmaking Queue is not working
TLDR; I can't get QueueName to work with matchmaking a turn-based match in Unity using matchmaking rules. Long version: I'm using the apple unity plugin found here: https://github.com/apple/unityplugins/blob/main/plug-ins/Apple.GameKit/Apple.GameKit_Unity/Assets/Apple.GameKit/Documentation~/Apple.GameKit.md I have created a Queue, RuleSet and a simple Rule to match players by following these docs tightly: https://developer.apple.com/documentation/gamekit/finding-players-using-matchmaking-rules. Here is the single rule I have that drives matchmaking: { "data" : { "type" : "gameCenterMatchmakingRules", "id" : "[hiddden-rule-id]", "attributes" : { "referenceName" : "ComplimentaryFactionPreference", "description" : "default desc", "type" : "MATCH", "expression" : "requests[0].properties.preference != requests[1].properties.preference", "weight" : null }, "links" : { "self" : "https://api.appstoreconnect.apple.com/v1/gameCenterMatchmakingRules/[hidden-rule-id]" } }, "links" : { "self" : "https://api.appstoreconnect.apple.com/v1/gameCenterMatchmakingRules" } } which belongs to a rule set which belongs to a queue. I have verified these are setup and linked via the App Store Connect API. Additionally, when I tested queue-based matchmaking without a queue established, I got an error in Unity. Now, with this, I do not. However there is a problem when I attempt to use the queue for matchmaking. I have the basic C# function here: public override void StartSearch(NSMutableDictionary<NSString, NSObject> properties) { if (searching) return; base.StartSearch(properties); //Establish matchmaking requests _matchRequest = GKMatchRequest.Init(); _matchRequest.QueueName = _PreferencesToQueue(GetSerializedPreferences()); _matchRequest.Properties = properties; _matchRequest.MaxPlayers = PLAYERS_COUNT; _matchRequest.MinPlayers = PLAYERS_COUNT; _matchTask = GKTurnBasedMatch.Find(_matchRequest); } The _PreferencesToQueue(GetSerializedPreferences()); returns the exact name of the queue I added my ruleset to. After this function is called, I poll the task generated from the .Find(...) function. Every time I run this function, a new match is created almost instantly. No two players are ever added to the same match. Further, I'm running two built game instances, one on a mac and another on an ipad and when I simultaneously test, I am unable to join games this way. Can someone help me debug why I cannot seem to match make when using a queue based approach?
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Sep ’25
How to verify with the appropriate signing authority that Apple signed the public key
Hello I trying to implement authentication via apple services in unity game with server made as another unity app On client side I succesfully got teamPlayerID signature salt timestamp publicKeyUrl According to this documentation https://developer.apple.com/documentation/gamekit/gklocalplayer/fetchitems(foridentityverificationsignature:)?language=objc I have to Verify with the appropriate signing authority that Apple signed the public key. As I said my server is special build of unity project So now I have this kind of C# programm to check apple authority over public certificate i got from publicKeyUrl TextAsset textAsset; byte[] bytes; textAsset = Resources.Load&lt;TextAsset&gt;("AppleRootCA-G3"); bytes = textAsset.bytes; rootCert.ChainPolicy.ExtraStore.Add(new X509Certificate2(bytes)); textAsset = Resources.Load&lt;TextAsset&gt;("AppleRootCA-G2"); bytes = textAsset.bytes; rootCert.ChainPolicy.ExtraStore.Add(new X509Certificate2(bytes)); textAsset = Resources.Load&lt;TextAsset&gt;("AppleIncRootCertificate"); bytes = textAsset.bytes; rootCert.ChainPolicy.ExtraStore.Add(new X509Certificate2(bytes)); rootCert.Build(cert); Where cert is X509Certificate2 object I ge from publicKeyUrl AppleIncRootCertificate AppleRootCA-G2 AppleRootCA-G3 is certificates I got from https://www.apple.com/certificateauthority/ But it is not work Anytime rootCert.Build(cert); return false Why it is not work? May be I build keychain using wrong root CA cert? Or whole approach incorrect? Please help
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Activity
Jun ’25
RealityKit not behaving as expected
This week, I developed a small multiplatform RealityKit project. I also created a demo scene in Reality Composer Pro. Afterward, I imported the local package into the project. Running the project on macOS works perfectly. However, when I tried to run it on my iPhone, I encountered a permission error indicating that it couldn’t read the package. This seems unusual to me because I assumed that the dependency is bundled into the binary file. In an attempt to resolve the issue, I pushed the RCP package to GitHub, hoping it would work. Fortunately, everything compiles successfully now, but the loading time is significantly long, and the animations don’t play on tap gestures. Could someone please help me identify the root cause of this problem?
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355
Activity
Jul ’25
GameKit Configuration File - Apple Documentation out of Date
This is the first time I have tried adding achievements to my games. The online documentation says: "Before you can access achievements in your code, you can configure them in Xcode and sync the configuration updates you make with App Store Connect. Begin configuring achievements by creating a GameKit configuration file. In Xcode, choose File > New > File from Template. Select GameKit File, and click Next. In the sheet that appears, enter a name for the configuration and click Create." Sounds easy - except Xcode 16.2 does not have a GameKit File as one of the Templates. Please advise on how to proceed and it would be nice if the documentation were updated.
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Activity
May ’25
PhotogrammetrySession fails with internal errors 4011 / 4012 when using iOS Object Capture (Area Mode) images
Hi all, I’m running into an issue when trying to reconstruct a 3D model using PhotogrammetrySession on macOS from a set of images captured via the iOS Object Capture sample app, specifically in Area mode. When I attempt to create the model from these images (using the raw Images/ folder exported directly from the capture session), I get the following errors: ERROR cv3dapi.pg: Internal error codes (2): 4011 4012 WARN cv3dapi.pg: Internal warning codes (1): 4507 Output error with code = -15 requestError: CoreOC.PhotogrammetrySession.Error.processError I use the "Images" directory directly exported from Object Capture with my iphone 12 pro max (has lidar) set to "area mode" in the object capture app here is an example heic image metadata from the sequence. heif-info Images/00044.869568833.HEIC MIME type: image/heic main brand: heic compatible brands: mif1, MiHE, MiPr, miaf, MiHB, heic image: 3024x4032 (id=49), primary tiles: 6x8, tile size: 512x512 colorspace: YCbCr, 4:2:0 bit depth: 8 thumbnail: 240x320 color profile: nclx alpha channel: no depth channel: yes size: 192x256 bits per pixel: 8 z-near: 1.173828 z-far: 2.552734 d-min: undefined d-max: undefined representation: uniform Z metadata: Exif: 960 bytes uri /tag:apple.com,2023:ObjectCapture#CameraTrackingState: 4 bytes uri /tag:apple.com,2023:ObjectCapture#CameraCalibrationData: 1015 bytes uri /tag:apple.com,2023:ObjectCapture#ObjectTransform: 48 bytes uri /tag:apple.com,2023:ObjectCapture#ObjectBoundingBox: 48 bytes uri /tag:apple.com,2023:ObjectCapture#RawFeaturePoints: 832 bytes uri /tag:apple.com,2023:ObjectCapture#PointCloudData: 23984 bytes uri /tag:apple.com,2023:ObjectCapture#BundleVersion: 5 bytes uri /tag:apple.com,2023:ObjectCapture#SegmentID: 4 bytes uri /tag:apple.com,2024:ObjectCapture#SessionUUID: 36 bytes uri /tag:apple.com,2024:ObjectCapture#CaptureMode: 4 bytes uri /tag:apple.com,2023:ObjectCapture#Feedback: 4 bytes uri /tag:apple.com,2023:ObjectCapture#WideToDepthCameraTransform: 48 bytes uri /tag:apple.com,2023:ObjectCapture#TemporalDepthPointClouds: 864026 bytes transformations: angle (ccw): 270 region annotations: none properties: camera intrinsic matrix: focal length: 2813.695557; 2813.695557 principal point: 1522.338502; 2002.843018 skew: 0.000000 camera extrinsic matrix: rotation matrix: -0.695 0.344 -0.632 0.007 -0.875 -0.483 -0.719 -0.340 0.606 Questions: • What do internal error codes 4011 and 4012 refer to? • Is there something specific about Area mode captures that require preprocessing before they’re compatible with PhotogrammetrySession? • Has anyone successfully reconstructed a model from an Area mode session using the stock Apple tools? NOTE: I can provide the folder of images for debugging if that would help!
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Activity
Jul ’25
How to customize shader code for visionos ?
Hello experts, I'm trying to implement a material with custom shader code, but I saw that visionOS doesn't allow you to inject custom Metal functions or use CustomMaterial like iOS/macOS, nor can you directly write Metal Shading Language (.metal) and use it through ShaderGraphMaterial. So my question is, if i want to implement your own shader code, how should i do it?
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Activity
Jul ’25
SKScene editor canvas gone
I've recently run into an issue in Xcode where the sks editor's preview canvas just vanishes for every project on my computer. I don't think it is an issue with my sks files because this works as expected on another computer with the same files, and when it happens it happens for ALL sks files in all projects. There used to be menu items to toggle the canvas and its settings, but those are now gone for me in sks files (they show up for swift files that have previews, however). Any idea what is going on here? How do I get the canvas back? I literally cannot get any work done on my primary computer because of this...
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Activity
Dec ’25
iPhone Pro Model - RefreshRate
I want to display the refresh rate on the screen of the iPhone (14 Pro Max), but each app of the App Store's "Floating Clock", "Floating Clock Premium" and "Screen Renewal Rate - RefreshRate Realtime" can only display two of 60Hz and 120Hz, and I wonder if it can display numbers of 1Hz, 10Hz, tens of Hz, or more than 3 levels. Does anyone know how to do it?
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Activity
Sep ’25
Custom GCController subclass for new hardware?
Hi all, Wondering how I would go about creating a plugin/class to support a new (physical/hardware) device with the game controller framework? Between GCVirtualController on iOS and the "KeyboardAndMouseSupport.bundle" I see inside GameController.framework on my Mac, it looks like the framework must be designed to support this but I can't find any documentation. Thanks!
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Activity
Jan ’26
Why does CanyonCrosser use both Class and Struct for RealityKit Systems?
In the CanyonCrosser example project, some RealityKit systems are implemented as classes while others are structs. What’s the reason for using different types?
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210
Activity
Aug ’25
Game Center fetchSavedGames sometimes returns empty list of games, although it works correctly on the next tries
I have implemented the Game Center for authentication and saving player's game data. Both authentication and saving player's data works correctly all the time, but there is a problem with fetching and loading the data. The game works like this: At the startup, I start the authentication After the player successfully logs in, I start loading the player's data by calling fetchSavedGames method If a game data exists for the player, I receive a list of SavedGame object containing the player's data The problem is that after I uninstall the game and install it again, sometimes the SavedGame list is empty(step 3). But if I don't uninstall the game and reopen the game, this process works fine. Here's the complete code of Game Center implementation: class GameCenterHandler { public func signIn() { GKLocalPlayer.local.authenticateHandler = { viewController, error in if let viewController = viewController { viewController.present(viewController, animated: false) return } if error != nil { // Player could not be authenticated. // Disable Game Center in the game. return } // Auth successfull self.load(filename: "TestFileName") } } public func save(filename: String, data: String) { if GKLocalPlayer.local.isAuthenticated { GKLocalPlayer.local.saveGameData(Data(data.utf8), withName: filename) { savedGame, error in if savedGame != nil { // Data saved successfully } if error != nil { // Error in saving game data! } } } else { // Error in saving game data! User is not authenticated" } } public func load(filename: String) { if GKLocalPlayer.local.isAuthenticated { GKLocalPlayer.local.fetchSavedGames { games, error in if let game = games?.first(where: {$0.name == filename}){ game.loadData { data, error in if data != nil { // Data loaded successfully } if error != nil { // Error in loading game data! } } } else { // Error in loading game data! Filename not found } } } else { // Error in loading game data! User is not authenticated } } } I have also added Game Center and iCloud capabilities in xcode. Also in the iCloud section, I selected the iCloud Documents and added a container. I found a simillar question here but it doesn't make things clearer.
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Activity
Dec ’25
Monthly recurring leaderboard and placement achievement?
I would like a monthly recurring leaderboard, but the most days one can set for the recurring leaderboard is 30, and some months have 31 days (or 28/29). This is dumb. I guess I have to manually reset a classic leaderboard each month to get this result? Additionally once it closes and is about to reset (I also have daily recurring leaderboards), I'd like to grant the top placers on the leaderboard a corresponding achievement, but I don't see any way of doing this. I believe I can do all these things on PlayFab, but it'll take a bit more work, and eventually cost. Any one have advise?
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Activity
Sep ’25
Gamekit Achievements Won't Unhide
Added achievements to my approved app. Added them for the next release version, which I am running in simulator. When I look at the Achievements page, I can see that there are 17 Achievements available (correct), but they all show as hidden, despite checking the "No" box in App Store Connect.
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Activity
May ’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