Hi, We are seeing watchdog-terminated app hangs reported by users on iOS 26. The hang occurs during cold launch when we set the Game Center authenticate handler. Our usage is straightforward — we follow the official guide: to set the handler once in the boot flow. localPlayer.authenticateHandler = ^(UIViewController *viewController, NSError *error){//handler code} The app never reaches our handler code. Instead, it is killed by the watchdog before the handler is invoked. Root Cause: We believe the root cause is GKDaemonProxy localPlayerAgeCategory makes a synchronous XPC call ( xpc_connection_send_message_with_reply_sync ) to the Game Center daemon ( com.apple.gamed ). The daemon does not respond, blocking the main thread indefinitely until the watchdog terminates the app. Also we haven't seen this before iOS 26. Reproduction Conditions: Unfortunately we don't have a consistent way to reproduce it. It happens intermittently. And I can't share the iOS build due to company requirements. I have pasted the stack trace below (all users report the similar stack tracks). Stack trace (representative, reported consistently across affected users): App Hang: The app was terminated while unresponsive 0 libsystem_kernel.dylib +0xcd0 _mach_msg2_trap 1 libsystem_kernel.dylib +0x4308 _mach_msg2_internal 2 libsystem_kernel.dylib +0x4228 _mach_msg_overwrite 3 libsystem_kernel.dylib +0x4074 _mach_msg 4 libdispatch.dylib +0x1c980 __dispatch_mach_send_and_wait_for_reply 5 libdispatch.dylib +0x1cd20 _dispatch_mach_send_with_result_and_wait_for_reply 6 libxpc.dylib +0x11ed8 _xpc_connection_send_message_with_reply_sync 7 Foundation +0x41710 ___NSXPCCONNECTION_IS_WAITING_FOR_A_SYNCHRONOUS_REPLY__ 8 Foundation +0x29068 -[NSXPCConnection _sendInvocation:orArguments:count:methodSignature:selector:withProxy:] 9 Foundation +0x69b7c -[NSXPCConnection _sendSelector:withProxy:arg1:] 10 Foundation +0x699e8 __NSXPCDistantObjectSimpleMessageSend1 11 GameCenterFoundation +0x986fc ___39-[GKDaemonProxy localPlayerAgeCategory]_block_invoke.109 12 GameCenterFoundation +0x1397d0 0x22cbde7d0 (0x22cbde794 + 60) 13 GameCenterFoundation +0x139610 0x22cbde610 (0x22cbde508 + 264) 14 GameCenterFoundation +0x139770 0x22cbde770 (0x22cbde6ec + 132) 15 GameCenterFoundation +0x98420 -[GKDaemonProxy localPlayerAgeCategory] 16 GameCenterFoundation +0x2ceb4 -[GKClientPreferencesSupport localPlayerAgeCategory] 17 GameCenterFoundation +0x93ba4 -[GKPreferences(AgeCategoryRestrictions) localPlayerAgeCategory] 18 GameCenterFoundation +0x93c34 -[GKPreferences(AgeCategoryRestrictions) getRestrictionLimitForLocalPlayer:] 19 GameCenterFoundation +0x93cd0 -[GKPreferences(AgeCategoryRestrictions) clampBoolRestriction:tableEntry:] 20 GameCenterFoundation +0x93d40 -[GKPreferences(AgeCategoryRestrictions) isBoolValueRestricted:tableEntry:] 21 GameCenterFoundation +0x9f7b8 -[GKPreferences(Restrictions) isBoolKeyRestricted:category:] 22 GameCenterUICore +0x2d04 -[GKLocalPlayerAuthenticator _authenticateUsingAuthUI:authenticationResults:usernameEditable:authUIDismissHandler:completionHandler:] 23 GameCenterUICore +0xd638 ___106-[GKLocalPlayer(AuthenticationPrivate) startAuthenticationForExistingPrimaryPlayerUponReturnToForeground:]_block_invoke 24 libsystem_trace.dylib +0xdb40 _os_activity_apply_f 25 GameCenterFoundation +0x181f4 -[GKActivity execute:] 26 GameCenterFoundation +0x18138 +[GKActivity named:execute:] 27 GameCenterUICore +0xd528 -[GKLocalPlayer(AuthenticationPrivate) startAuthenticationForExistingPrimaryPlayerUponReturnToForeground:] 28 libsystem_trace.dylib +0xdb40 _os_activity_apply_f 29 GameCenterFoundation +0x181f4 -[GKActivity execute:] 30 GameCenterFoundation +0x18138 +[GKActivity named:execute:] 31 GameCenterFoundation +0x4f124 ___40-[GKLocalPlayer setAuthenticateHandler:]_block_invoke 32 libdispatch.dylib +0x1b1e0 __dispatch_client_callout 33 libdispatch.dylib +0x45ac __dispatch_once_callout 34 GameCenterFoundation +0x4f070 -[GKLocalPlayer setAuthenticateHandler:] Additional Notes: This issue was not observed prior to iOS 26. We have no reports of this on iOS 17 or iOS 18. We are unable to share a build due to company policy. We cannot reproduce this consistently — it occurs intermittently in production. All affected users report the same stack trace pattern.

When I enter webp image to the assets catalog I get warrning: /Users/..../Assets.xcassets The image set "Card-Back" references a file "Card-Back.webp", but that file does not have a valid extension. It works, I see all my images perfect. How can I fix the 200+ warrnings?

Xcode hangs when I call PhotogrammetrySession(input: [PhotogrammetrySample]) with objectMask set and traps on some devices, see the attached screenshot, it gets to the function and hangs. Even the folder reconstruction also doesn't complete as it can't find alignment and displays the CoreOC.PhotogrammetrySession.Error 6 and I understand to mean alignment failed. In this case it failed while object masking was ON, so RealityKit could not find enough consistent feature tracks inside the masked pixels across the image set. What can be done or do you guys expose any functions that can be used to aid, or handle these internally, can't find any internally. The ObjectMasks are actually segmentation masks from an ML algorithm . To replicate try calling PhotogrammetrySession(input: [PhotogrammetrySample]) with contentsOf as captured on your documentation, even with like 30 image set or is there something I'm missing. I will appreciate a timely response and willing to provide more clarity and informations, thank you so much for your understanding

Hi everyone, I’ve spent the last 2 months pulling off a wild solo experiment: building a complete mobile puzzle game from scratch using Unreal Engine, where over 100k lines of code (C++ & pipelines) and thousands of 3D/UI assets were entirely generated by various AI models. Before anyone rolls their eyes—no, AI didn't replace the game designer here. AI provided the brute-force production muscle, but I gave it its soul. Every single bit of core design—the underlying math models, difficulty pacing, and counter-mechanics for the dynamic gimmick bosses—was designed and balanced by me. The game itself is a tactical, gimmick-boss driven match-3. I got tired of the usual candy-coated reskins and wanted to make something with rigid logic, irregular board topologies, and tight move economies for people who actually like strategic puzzle-solving. I’m currently running a closed beta via TestFlight on iOS to stress-test the build, and I'd love to get some brutal feedback from fellow devs. (Just a heads up: save progress won't carry over to final release). You can grab the build directly here: https://testflight.apple.com/join/VnUWvHFC I’m specifically looking for insights on: Performance & Thermals: How does the UE rendering pipeline handle on your device during heavy chain reactions? Aesthetic Cohesion: Does an all-AI asset pipeline manage to feel like a unified universe, or do you feel that "AI uncanny valley"? Balance: Do the non-Euclidean layouts and boss disruption mechanics feel strategic or just plain frustrating? I'll be hanging out in the comments. Drop any questions you have about prompt-engineering a 100k-line codebase, solo pipeline management, or UE integration. Thanks for testing!

Hi everyone, I’ve spent the last 2 months pulling off a wild solo experiment: building a complete mobile puzzle game from scratch using Unreal Engine, where over 100k lines of code (C++ & pipelines) and thousands of 3D/UI assets were entirely generated by various AI models. Before anyone rolls their eyes—no, AI didn't replace the game designer here. AI provided the brute-force production muscle, but I gave it its soul. Every single bit of core design—the underlying math models, difficulty pacing, and counter-mechanics for the dynamic gimmick bosses—was designed and balanced by me. The game itself is a tactical, gimmick-boss driven match-3. I got tired of the usual candy-coated reskins and wanted to make something with rigid logic, irregular board topologies, and tight move economies for people who actually like strategic puzzle-solving. I’m currently running a closed beta via TestFlight on iOS to stress-test the build, and I'd love to get some brutal feedback from fellow devs. (Just a heads up: save progress won't carry over to final release). You can grab the build directly here: https://testflight.apple.com/join/VnUWvHFC I’m specifically looking for insights on: Performance & Thermals: How does the UE rendering pipeline handle on your device during heavy chain reactions? Aesthetic Cohesion: Does an all-AI asset pipeline manage to feel like a unified universe, or do you feel that "AI uncanny valley"? Balance: Do the non-Euclidean layouts and boss disruption mechanics feel strategic or just plain frustrating? I'll be hanging out in the comments. Drop any questions you have about prompt-engineering a 100k-line codebase, solo pipeline management, or UE integration. Thanks for testing!

My game supports both GameCenter, setting up a custom host and local games against bots. To log in to GameCenter and be able to handle invitations from other players, I set GKLocalPlayer.local.authenticateHandler after the app finished loading. But it seems that whenever I’m disconnected from the internet for more than 24 hours, setting GKLocalPlayer.local.authenticateHandler causes the whole window to be obfuscated by an alert telling me that I have no internet connection. When this happens, if I connect to the internet and disconnect again, the alert is not shown anymore. This is a huge problem because the alert prevents a user from using any other feature of the app unrelated to GameCenter, since there's no way to dismiss it. Is this really intended behaviour or how is a user supposed to continue using the app that supports GameCenter and does not rely on it, while being disconnected from the internet? I created FB22951946.

I'm making an apple watch game and it's running so smooth and nice while developing but I ran into a showstopping problem that I wouldn't even have noticed until i deleted the app and reinstalled... Every first-run on a freshly installed copy of the game has major frame hitches as it loads assets. Every run after that has ZERO hitches and runs like butter. Even if i install a new version on top of the old one (which is why i never noticed this problem in my almost finished game) it runs smooth. Framerate issues come back if I delete and reinstall. I think it's compiling shaders or caching geometry but I haven't been able to trick it into doing the hard work during non-critical moments in the game. I've tried preloading assets in the main menu, loading at the start of the level, loading and rendering in a tiny part of the screen, rendering behind dialog boxes... it seems no matter what i can only get rid of the frame hitches after the game has been played through once... and I'm going to lose all customers on that first terrible impression even though the game is actually really good and fun when it's running properly... Any suggestions how i can prewarm/precompile the assets to avoid framerate hitches and freezes during gameplay? I thought I was so close to release but I feel this is un-shippable! I can send a link to my test flight build to anyone that wants to see the problem first hand. Also please note that I am artist-forward with a technical lean, but certainly not a real programmer, unfortunately. Jiovanie

The WWDC videos like the new "Boost your graphics performance with the M5 and A19 GPUs" contain extremely valuable information and tips on how to discover, diagnose and remedy performance issues. They seem to serve as quick reminders and distilled summaries of more comprehensive documentation that I assume can be found somewhere. Where do we find the underlying comprehensive documentation that explains Apple Silicon GPU architecture? How can I learn to understand the basis of the data presented by the Xcode Metal Debugger? Any hints at external literature and resources are welcome.

The WWDC videos like the new "Boost your graphics performance with the M5 and A19 GPUs" contain extremely valuable information and tips on how to discover, diagnose and remedy performance issues. They seem to serve as quick reminders and distilled summaries of more comprehensive documentation that I assume can be found somewhere. Where do we find the underlying comprehensive documentation that explains Apple Silicon GPU architecture? How can I learn to understand the basis of the data presented by the Xcode Metal Debugger? Any hints at external literature and resources are welcome.

I am processing large images where each output pixel depends on a large neighborhood of surrounding pixels. As a result, the shader performs a very high number of texture sampling operations, which appears to cause cache misses and becomes a performance bottleneck. Since neighboring threads often process adjacent pixels, many of the sampled pixels overlap between threads. Although each thread operates on a slightly different output pixel, a large portion of the texture accesses are effectively identical. Does Metal provide mechanisms that allow neighboring threads to share or synchronize intermediate results in order to reduce redundant texture fetches? Are there recommended approaches for exploiting data reuse across threads, for example through threadgroup memory or other Metal-specific features? In this type of workload, how effective is texture gathering (gather) for reducing sampling overhead, especially when only the RGB channels of an RGBA texture are required? Would using gather generally improve cache utilization and performance in this scenario? When using gather, what is the preferred way to handle texture borders and edge conditions without introducing per-thread branching (e.g., explicit if statements)? Any recommendations for optimizing large-radius neighborhood operations in Metal would be greatly appreciated.

Are there opportunities for developers to use Apple Intelligence models through Metal in ways that unlock new rendering, simulation, or real-time content generation techniques?

At which time does Metal allocate and deallocate memory for textures? I've observed that the textures live for the whole time of the commandBuffer. So, if I have multiple large textures that I need in subsequent shaders, it would make sense to work with multiple commandBuffers to enable deallocation in order to reduce peak memory usage. Is that correct? Do you have any other suggestions on how to reduce peak memory usage when working with large metal textures? Hint: I am using compute shaders only.

What's the recommended pattern for sharing a complex SpriteKit game scene (and basic game code) between iOS and watchOS targets without code duplication, given the platform differences in input and rendering?

Hi! Question Could you provide some reassurance on the continued support for SpriteKit in the coming years? Trigger The deprecation of SceneKit at WWDC 2025 made me nervous. Context I use SpriteKit because: It can render any video AVFoundation can handle, which third-party engines don't do for several reasons including patents. This allows me to prototype UI that controls video with a game-like feel. It can render text and emojis through AttributedString, and text is hard. Thanks to a clear and well-exposed update loop, it can be integrated with libraries such as Core Image or Box2D. Example with Box2D here. It can draw dynamic shapes and paths with SKShapeNode, and visualize and respond to all the processing done at specific times during a frame. SKView is very handy to generate textures from nodes, and SKRenderer can be used to render a SpriteKit scene to video or sequence of images. This is possible thanks to multiple frameworks working together, including AVAssetWriter and IOSurface. Example of SpriteKit offline rendering here. Apple Alternatives When Apple announced the deprecation of SceneKit, I learned RealityKit in order to move my SpriteKit-based projects to RealityKit. RealityKit is interesting, but for 2D and 2.5D workflows I found several areas where SpriteKit remains significantly more practical: I had to lock physics to the XY plane, which could stress the engine and introduce unwanted overlap. Overlapping entities on a 2D plane was hard: ModelSortGroup did not provide the simple flexibility that SpriteKit zPosition provides. AFAIK there is no dynamic path/shape drawing in RealityKit. So drawing lines, visualizing physics and joints, rendering graph connections in the scene is not as easy as it is with SpriteKit shape nodes. SpriteKit is lighter and less power-hungry. Let me know if you need any more context or detail. Thank you!

The developer documentation for Rosetta describing its end of support (https://developer.apple.com/documentation/apple-silicon/about-the-rosetta-translation-environment) says the following: Beyond this timeframe, we will keep a subset of Rosetta functionality aimed at supporting older unmaintained gaming titles, that rely on Intel-based frameworks. Are there details about which specific functionality this is? And as a concrete example, will parts of Rosetta that are needed by programs used to run and/or evaluate Windows games, such as WINE or CrossOver, remain supported?

My app contains hundreds of games, each of which would benefit from its own set of achievements, leaderboards, etc. Is there any hope for minigame support in GameKit?

I've coded a text-adventure game in SwiftUI. (My game has no graphics or sound effects.) My app already supports keyboard navigation; I would like to add support for game controllers on iPhone. I can't figure out how to do it. I especially can't see any way to allow controller users to enter text in a TextField. I've read https://developer.apple.com/documentation/gamecontroller/supporting-game-controllers and it's all about button events. There's no reference to SwiftUI at all in that documentation, or any input-method editing at all. The only mention of "keyboard" is about treating the keyboard itself as if it were a game controller providing button events. How do I implement this?

I guess this is not an actual video Group Lab. sigh Would love to see a dedicated Reality Composer Pro 3 session - even for those of use actual Vision Pro devs that didn't get the lucky golden ticket to the Apple Park event. You need to make these interactions available to us in person during WWDC week. That all being said... How do I go about baking lighting in RCP3? I cannot find anything in the documentation. Thanks!

If you have a "launcher-type app" (a regular macOS app bundle) which is used to launch the actual game executable (a non-bundled executable, such as a Java game), Game Mode does not seem to work as desired in this case. If the launcher app has the appropriate LSSupportsGameMode and LSApplicationCategoryType set, the launcher app will activate Game Mode if fullscreened but the actual game will not (FB18026957). Is there a workaround for this? It also seems like the system hardcodes some apps to act as "game launcher apps" which do have the desired behavior - for example, if you have a sample app set to Steam's bundle identifier (or just use Steam to run the program) and have this architecture where it runs another executable which is the real game, then that game can inherit Game Mode, which is also supported by system logs in Console (note the "launcher" labelReason): default 17:11:05.008533-0400 gamepolicyd Found game GameProcess(Optional("java"), pid=33754, euid=501, labelReason=launcher, launchedBy=Steam) Is there a way to opt into or apply for this behavior for our own apps? I previously asked this on the forums but I'm also wondering if any new developments have occurred since then.

Hi, What's the best way to handle drastic changes in scene charateristics with the new MTLFXTemporalDenoisedScaler? Let's say a visible object of the scene radically changes its material properties. I can modify the albedo and roughness textures consequently. But I suspect the history will be corrupted. Blending visual information between the new frame and the previous ones might be a nonsense. I guess the problem should be the same when objects appear or disappear instantly. Is the upsacler manage these events for us (by lowering blending), or should we use the reactive or the denoise strength mask or something like that to handle them?