Processes & Concurrency

RSS for tag

Discover how the operating system manages multiple applications and processes simultaneously, ensuring smooth multitasking performance.

Concurrency Documentation

Posts under Processes & Concurrency subtopic

Post

Replies

Boosts

Views

Activity

Processes & Concurrency Resources
General: DevForums subtopic: App & System Services > Processes & Concurrency Processes & concurrency covers a number of different technologies: Background Tasks Resources Concurrency Resources — This includes Swift concurrency. Service Management Resources XPC Resources Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com"
0
0
585
Jul ’25
I want to bang my head into a brick wall
I had the issue pop up again. To refresh what previously happened, when I would submit a new build to TestFlight, it wouldn’t let me download it. That was a problem for a couple weeks. Then after the problem resolved I was able to download the “new build” but when I went into the app, it was clearly an old one. This issue got resolved a couple weeks ago, now it’s back. When I went to test out the new build on a couple of my apps, I was able to download it, but when I looked through the app, it was an old one. Please help me resolve this fast. Last time I waited for over a month
0
0
48
16h
iOS 26.5 SIGKILLs audio-recording app at ~50s of background despite UIBackgroundModes: audio - what is the supported API path?
Hi, hoping for guidance on what's a long-running bug for our app. The problem We have a transcription app on iPhone 17 Pro Max running iOS 26.5. Recording flow uses AVAudioEngine.installTap(onBus:) to capture PCM into a JS bridge for streaming to a remote transcription service. A parallel AVAudioRecorder writes the same audio to disk as backup. When the user starts a recording and locks the phone, iOS terminates our process with SIGKILL at approximately 50 seconds of continuous background time, despite: UIBackgroundModes includes audio (verified in shipping IPA's Info.plist) AVAudioSession.setCategory(.playAndRecord, mode: .default) is active AVAudioEngine is running with installTap producing PCM buffers right up to the moment of death UIApplication.backgroundTimeRemaining returns Double.greatestFiniteMagnitude at applicationDidEnterBackground (verified in our event log) No AVAudioSession.interruptionNotification is delivered before the kill. iOS terminates the process cleanly with no warning event to our observer. Evidence Our Swift observer module writes an event log to disk on every system event. On relaunch we ship it to our crash reporter. Excerpt from a recent kill on iOS 26.5 / build 2.1.32: T=0.000s session-start (engineRunning: true) T=57.199s app-will-resign-active (bufferCallbackCount: 22) T=58.913s app-did-enter-background (backgroundTimeRemaining: infinity, bufferCallbackCount: 39) [no further audio events captured] [Swift heartbeat written every 5s for next ~46 seconds] T~105s Process SIGKILLed (heartbeat last-alive: 09:31:01.597Z) Background time before kill: ~46 seconds. engineRunning: true and bufferCallbackCount was still incrementing at the moment the event log stops capturing - the audio engine was alive and feeding buffers when iOS terminated us. What we've tried (35 documented attempts) Hopefully not all relevant but listing for completeness: Various AVAudioSession category/mode/options combinations (Default, Measurement, VoiceChat, .mixWithOthers, .defaultToSpeaker, .allowBluetoothHFP) Parallel AVAudioRecorder writing a .caf file as a "real recording app" signal SFSpeechRecognizer with requiresOnDeviceRecognition = true consuming PCM in-process (50s request rotation) BGContinuedProcessingTask with Progress.completedUnitCount reporting monotonic progress every 5 seconds Live Activity (ActivityKit) with NSSupportsLiveActivitiesFrequentUpdates = true Live Activity update pushes via APNs (confirmed wake widget extension only, not host) Silent device-token APNs background pushes (confirmed iOS ~5/day rate limit) CallKit fake call (CXProvider + CXCallController) - works but creates the green pill UI which our product can't ship WebRTC peer connection with active media stream (via react-native-webrtc loopback) UIBackgroundModes: voip declaration (without CallKit) beginBackgroundTask + engine bounce (Apple's own guidance says don't, our test confirmed it's actively harmful) CLLocationManager background updates All die at ~50s background. None of them survive. What works on the same device Three App Store transcription apps survive indefinite background recording on our exact device + iOS version. We have inspected their IPAs (Mach-O LC_LOAD_DYLIB analysis + embedded entitlement extraction): Otter (com.aisense.otter) - UIBackgroundModes: audio + fetch + processing + remote-notification. Uses OneSignal-driven Live Activity push tokens + NotificationServiceExtension. No CallKit, PushKit, or WebRTC. Granola (com.granola.ios-prod) - has UIBackgroundModes: voip but the voip is for their separate outbound-phone-call feature (TwilioVoice + CallKit, lives in their PhoneCalls.framework). Recording-path uses ONLY AVAudioRecorder + PlayAndRecord + ModeDefault + Live Activity with frequentPushesEnabled. Zero PushKit anywhere in the bundle. Transcribe Speech to Text by DENIVIP (ru.denivip.transcribe) - the smallest API surface: UIBackgroundModes: audio + remote-notification only. AVAudioEngine + .playAndRecord + .default + SFSpeechRecognizer consuming PCM. No CallKit, PushKit, BGTask, Live Activity, WebRTC, or VoIP. Three apps, three different mechanisms, all working. We've implemented bits of all three approaches in our app and still die at 50s. Apple Voice Memos (system app, private entitlements) also survives indefinite recording on the same device. Questions What is the supported API path for indefinite background microphone-only recording on iOS 26.5? Voice Memos and competitor apps clearly accomplish this - what's the missing piece? Why does UIApplication.backgroundTimeRemaining return Double.greatestFiniteMagnitude at applicationDidEnterBackground but the process is terminated ~50 seconds later? Is the meaning of this property changing in iOS 26? What causes the iOS 26 process scheduler to revoke the audio-mode background runtime classification? No AVAudioSession.interruptionNotification is delivered before SIGKILL. Where can we observe the classification change? Does iOS 26 distinguish "audio recording with no audible output" from "audio recording with audible output (e.g. a media playback session)"? If so, what is the supported API to register as a recording-only background-audio app? Does BGContinuedProcessingTask (new in iOS 26) actually extend background CPU time for an app that is also using UIBackgroundModes: audio and an active AVAudioSession? Or is it for finish-what-you-started bursts only (per WWDC 2025 session 227)? Any guidance - even pointers to specific WWDC sessions, sample code, or technotes - would be hugely appreciated. We've spent ~40+ hours on this and want to know what the supported path looks like in iOS 26. Happy to share more event-log data, IPA inspection notes, or build a focused Xcode reproduction if helpful. Thanks!
1
0
126
3d
iPadOS 26.4+ significantly reduced per-app memory limit from 6GB to 3GB on 8GB iPad, breaking memory-intensive apps
Summary: Starting from iPadOS 26.4, the maximum memory available to a single app has been reduced from approximately 6GB to 3GB on an 8GB iPad. This change persists in iPadOS 26.5 and has not been addressed. This breaks core functionality of memory-intensive applications such as 3D scanning apps that require large amounts of RAM to process models. Device: iPad with 8GB RAM Affected versions: iPadOS 26.4, iPadOS 26.5 Working version: iPadOS 26.0 / 26.1 / 26.2 / 26.3 Measured Data: iPadOS 26.0–26.3: App available memory ≈ 6GB (75% of total RAM) iPadOS 26.4–26.5: App available memory ≈ 3GB (37.5% of total RAM) Measurement method: Apple system API Impact: This is a regression, not expected behavior. The available memory per app has been cut by 50% without any official documentation or release notes mentioning this change. As a result, our 3D scanning application crashes immediately when attempting to process 3D models on iPadOS 26.4 and later. The app requires substantial RAM to load and process 3D model data. With only 3GB available, memory allocation fails during model processing, causing the app to crash (EXC_RESOURCE / OOM kill). This core functionality was working correctly on iPadOS 26.3 and earlier with the same device and same app binary. This regression makes our app's primary feature completely unusable for all users on iPadOS 26.4+. Steps to Reproduce: On an 8GB iPad, install iPadOS 26.0 Measure available app memory using Apple system API Upgrade to iPadOS 26.4 or 26.5 Measure available app memory again Observe: available memory drops from ~6GB to ~3GB Expected Result: Available memory per app should remain consistent across minor OS updates, or any changes should be documented. Actual Result: Available memory per app dropped by 50% starting in iPadOS 26.4, with no documentation of this change. Additional Notes: Disabling Apple Intelligence does not resolve the issue This issue was not fixed in iPadOS 26.5 Other developers have reported increased crash rates starting in iPadOS 26.4 (Apple Developer Forums)
1
0
109
4d
XPC Communication between Editor app and user-compiled code
Hello! I'm trying to implement an editor app (macOS) that allows the user to write code, which will be compiled and executed, showing the result in the editor window. Imagine it like SwiftUI previews, but the graphic output is created with Metal, not SwiftUI. I found that IOSurface can be used to share that kind of data over XPC, so I would not have to rely on the private NSRemoteView. However, I'm confused if it is, at all, possible for my editor app to connect to an XPC Service, that was NOT bundled with it (but compiled by it at runtime). I succeeded to launch an XPC service defined as: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>Label</key> <string>com.myteam.myproject.service</string> <key>MachServices</key> <dict> <key>com.myteam.myproject.service</key> <true/> </dict> <key>Program</key> <string>/Path/to/service/run_my_service.sh</string> </dict> </plist> But the call to let connection = NSXPCConnection(machServiceName: "com.myteam.myproject.service") let proxy = connection.remoteObjectProxyWithErrorHandler { error in continuation.resume(throwing: error) } as? MyServiceProtocol fails with "The connection to service named com.myteam.myproject.service was invalidated: Connection init failed at lookup with error 3 - No such process." I have added <key>com.apple.security.temporary-exception.mach-lookup.global-name</key> <array> <string>com.myteam.myproject.service</string> </array> to my entitlements. Since the tutorials I followed are quite old, I'm wondering if support for something like this was dropped at some point. Thanks for any advice!
6
0
425
5d
iOS feasibility question: user-initiated wake-word detection during active session
Hi all, Technical architecture question for those experienced with iOS background audio / microphone constraints. I’m exploring an app concept where: the user explicitly starts a temporary active session during that session, on-device wake-word / keyword detection runs locally no audio is stored or transmitted during passive monitoring monitoring stops when the user ends the session The intended UX is that the user may then lock the phone or place it away while the active session remains in progress. Question: Is there any App Store-compliant architecture that would allow local keyword / wake-word detection to continue while the device is locked or the app is backgrounded during that active session? Or would iOS lifecycle / background execution rules make this infeasible for custom wake-word detection? Interested in practical experience around: AVAudioSession background audio modes on-device speech processing App Review acceptability Thanks in advance.
0
0
192
5d
SMAppService - helper is not started
My software installs a privileged daemon using the SMAppService api. After removing the executables and recompiling the software I sometimes find that it needs to be registered again. After doing this, i.e. ensuring the application is properly registered and enabled in Login Items & Extensions the helper is not run when initiated from XPC. SMAppService.status has returned .enabled, and there is a valid job dictionary for the helper. I check the job dictionary with a function called updatePenaltyBoxStatus() that was given to me by a friend but I think originated from Apple. If I logoff (or reboot), login again, manually open Login Items & Extensions to check registration, then retry the application, it works. I don't mind doing this but it is probably a bit much for a lot of my users. Is there a reliable way to do this programatically? Here is my Swift translation of updatePenaltyBoxStatus. I fetch the job dictionary with SMJobCopyDictionary() prior to calling isInPenaltyBox(). I also had to write C wrapper functions for the WIFEXITED and WIFEXITSTATUS macros. func isInPenaltyBox(_ dict: Dictionary<String, Any>?) -> Bool { guard let jobDict = dict else { // If the helper was in the penalty box, unregistering it doesn't change that. So don't override a previous helperInPenaltyBox value return m_penalty_box } if let lastExitStatusObj = jobDict["LastExitStatus"] as? NSNumber { let lastExitStatus = lastExitStatusObj.intValue if wifexited(Int32(lastExitStatus)) == 0 { // It might've stopped or exited due to a signal or whatever. // Regardless, it didn't meet our criteria for winding up in the penalty box. m_penalty_box = false } // Now get the exit status and check for `EX_CONFIG`. let status = wexitstatus(Int32(lastExitStatus)) let newInPenaltyBox = status == EX_CONFIG if m_penalty_box != newInPenaltyBox { Logger.instance.log( "Penalty box change: " + m_ident + " old: " + String(m_penalty_box) + " new: " + String(newInPenaltyBox)) } m_penalty_box = newInPenaltyBox } return m_penalty_box }
2
0
259
2w
Background Assets: Downloaded .aar not working — "bundle record couldn't be looked up" error (-10814)
Platform: iOS 26 (23E254) Xcode: 26.0 Reproduces on: Debug builds AND TestFlight Summary: I'm using Apple-Hosted Managed Background Assets with on-demand download policy. The .aar archives download successfully (correct file size, status = downloaded), but the contents are never extracted into the asset pack namespace. AssetPackManager.shared.contents(at:) returns fileNotFound for all path variants, and url(for: FilePath(".")) returns a URL that exists but contains zero children. Root Cause from Sysdiagnose: The backgroundassets.user daemon logs reveal this error on every download attempt: A bundle record couldn't be looked up for the application identifier "AtlasDrift.SnapTrail": Error Domain=NSOSStatusErrorDomain Code=-10814 "(null)" UserInfo={_LSFile=LSBindingEvaluator.mm, _LSLine=1973, _LSFunction=runEvaluator} Error code -10814 is kLSApplicationNotFoundErr. The BA daemon downloads the .aar blob, then attempts to find the app bundle via LaunchServices to locate the extension for extraction — but the LS lookup fails. Without the extension, extraction never occurs. Verified Configuration Everything matches the documentation and WWDC sessions: Extension embedded at SnapTrail.app/Extensions/BackgroundDownloadExtension.appex Bundle IDs: App = AtlasDrift.SnapTrail, Extension = AtlasDrift.SnapTrail.BackgroundDownloadExtension (correct parent-child pattern) Extension point: com.apple.background-asset-downloader-extension Product type: com.apple.product-type.extensionkit-extension Protocol: StoreDownloaderExtension from StoreKit (for Apple-hosted packs) App group: group.AtlasDrift.SnapTrail (matching in both app and extension entitlements) Info.plist keys: BAAppGroupID, BAHasManagedAssetPacks = YES BAUsesAppleHosting = YES (no BAInitialDownloadRestrictions or other BA keys) .aar Packaging Archives built with xcrun ba-package from the Assets directory. Manifest format: { "assetPackID": "ireland", "downloadPolicy": { "onDemand": {} }, "fileSelectors": [{ "directory": "POIRegions/ireland/IR" }], "platforms": ["iOS"] } Uploaded via App Store Connect API with assetType: "ASSET". Diagnostic Observations AssetPackManager.shared.assetPack(withID:) returns valid metadata (correct download size) ensureLocalAvailability(of:) completes without error assetPackIsAvailableLocally(withID:) returns true url(for: FilePath(".")) returns a URL that exists but has zero children (empty namespace) contents(at:) returns fileNotFound for all path variants tested The extension never runs — breadcrumb file written in init() is never created The -10814 error appears in daemon logs for every download cycle Questions Has anyone successfully used Apple-Hosted Managed Background Assets on iOS 26 beta? Is the daemon's LaunchServices integration known to be broken in this seed? Is there anything about the bundle identifier format or provisioning profile setup that could cause the BA daemon's LS lookup to fail, even though the app installs and runs fine otherwise? Are there any additional Info.plist keys or entitlements beyond what's documented that might be required for the daemon to locate the app bundle? Any guidance would be appreciated. I've filed a Feedback report with the full sysdiagnose attached.
1
0
240
2w
applicationWillTerminate to wrap up Background Recording
Hello together, the user is able to do recordings with my app. The recordings also runs, while the App is in Background. I have Background Modes Audio & Background enabled. When the user accidentally terminates the App while the recording is still running, the whole recording is lost. I tried AppDelegate applicationWillTerminate on my iOS 26 App and it works perfectly to wrap up the LiveActivity that is shown while the recording is active. But it does not save the Audio and also doesn't update the Widgets (they are interactive and show a different state while recording and stay stuck in recording-state on accidental termination). Any ideas? Best wishes, Dominik
2
0
223
2w
Safari web extensions: Optimal IPC architecture between extension and the containing app
I'm building a macOS safari extension and porting its functionality from a chrome extension. The chrome extension uses native messaging hosts to communicate with another process using IPC and holding a persistent connection. To use the same functionality in Safari, I understand that will need to use the handler to communicate it to the containing app, and the app will have to hold the persistent IPC connection. My question derives from that concept: should the app be running in a long-lived state? And if so, how can I ensure that app be running 100% of the time. Also is there any way I can control it's lifecycle with the Safari browser's lifecycle? I will not be using XPC here, but a different UDS to make the connection. Also in addition to that, what would you recommend the best approach is the communicate between the extension and it's handler? -> should it be again a UDS or userDefaults +darwin notification be enough? Also I wouldn't want the inter-message relayed between components to be dropped, is there a fault tolerant architecture you would recommend?
0
0
178
3w
Unable to set subtitle when BGContinuedProcessingTask expires
Hi, I've now identified a few areas when BGContinuedProcessingTask gets expired by the system no progress for ~30 seconds high CPU usage high temperature Some of these I can preempt and expire preemptively and handle the notification, others I cannot and just need to let the failure bubble up. When the failure does bubble up, I'd like to update the title and subtitle. I'm able to update the title, but the subtitle is fixed at "Task Failed" Is there any workaround? Or shall I file a bug here?
1
0
357
Apr ’26
Best practice for replacing deprecated sem_init/sem_wait in a cross-platform threading layer on macOS (arm64)
Hi all, I'm working on a cross-platform runtime that manages a pool of threads (think game engine / emulator style... dozens of guest threads mapped 1:1 to host pthreads). It was originally written for Linux and Windows and we're now porting to macOS on Apple Silicon. We've hit a wall with a deadlock on macOS and traced it back to our use of POSIX unnamed semaphores (sem_init / sem_wait / sem_post) for thread suspend and resume. We were unaware these have never actually been implemented on macOS, sem_init silently returns -1 with ENOSYS and then sem_wait just hangs forever. That explains our deadlock. The tricky part is how we use them. Our suspend mechanism works by sending SIGUSR1 to a target thread via pthread_kill. The signal handler then calls sem_wait to block the thread in place until another thread calls sem_post to resume it. So whatever we replace sem_init/sem_wait with needs to be safe to call from inside a signal handler. From what I can tell: dispatch_semaphore_wait is not documented as async-signal-safe pthread_cond_wait is also not async-signal-safe os_sync_wait_on_address looks promising but requires macOS 14.4+ which is a pretty high floor We could spin on a std::atomic with .wait() / .notify_all() but I've seen reports of high wake latency (up to 15ms) in libc++'s implementation on macOS My questions: What's the recommended way to block a thread inside a signal handler on macOS? Is there an async-signal-safe wait primitive I'm missing? Would restructuring to avoid blocking in the signal handler entirely be the better approach? For example, having the signal handler just set an atomic flag and then checking it at yield points — would that be the expected pattern on macOS? For the non-signal-handler suspend/resume paths, is dispatch_semaphore_t the right replacement for sem_t, or is there something better suited for high-frequency thread synchronization in 2026? Separately, we're also using ucontext (makecontext/swapcontext) for a fiber system on macOS and hitting issues on native arm64, it works under Rosetta but breaks natively. We have a setjmp/longjmp + manual stack pivot backend we can switch to. Is there any plan to fix or un-deprecate the ucontext functions on arm64, or should we just move off them permanently?
2
0
204
Apr ’26
iOS: Issues getting beginBackgroundTaskWithName working reliably
We have tried using background tasks for file saving via (UIBackgroundTaskIdentifier) beginBackgroundTaskWithName:(NSString *) taskName expirationHandler:(void (^)(void)) handler; when our app goes into the background and/or is closed by the user. But we cannot make it work the way the documentation tells us it should. While task creation never reports an issue (in fact it never calls our expiration handler at all) and the returned task id is always valid, when we ask for how much time we have left via backgroundTimeRemaining we always get 6s instead of the specified 30s. We tried to create the task when the app state goes to inactive or when our delegate is called via applicationDidEnterBackground but it makes no difference, besides the fact that the remaining time reported is basically max double, when the app is not in background yet which is by design as far we understand. But we don't even get the 6s for saving when a user closes the app. Because almost immediately after applicationDidEnterBackground our delegate is called via applicationWillTerminate which will then again almost immediately end in the app receiving a SIGKILL. So we must be doing something wrong. Why would applicationWillTerminate be called at all when we have a valid background task that reports we have 6s left? We tried blocking the thread in both background and terminate to at least give us the 5s the spec says we have before we get the SIGKILL. That works in general but doesn't feel like the correct approach and we do need more time than the 5s or 6s we get this way. Are we supposed to add something to our plist in order for these background tasks to work correctly? It is very confusing that there is a second mechanism that's also called background tasks for running apps in the background in general, which is not applicable to us. Are we supposed to block somewhere when we create the task? Or even spin up an extra thread for the task? Why is our expirationHandler never called? The spec says that our handler should be called if it was unable to "grant the ask assertion" so it seems like we do not have that problem. But it's also supposed to be called just before we are running out of time but by that time the app is already dead. This was all tested on iOS 26.3 and it is probably worth mentioning that our app is Qt-based.
4
0
266
Apr ’26
How to debug a Launch Daemon that requires an App Group provisioning profile for XPC communication
Hello, I am developing a macOS Launch Daemon (packaged as a bundle) that acts as an XPC server. For debugging purposes, I am trying to run the daemon's executable directly from the terminal via sudo ./mydaemon.app/Contents/MacOS/myexecutable. Initially, I added the com.apple.security.application-groups entitlement to the daemon. However, when starting the process, it failed to create the XPC service with the following errors: Unsatisfied entitlements: com.apple.security.application-groups Soft-restriction provisioning profile validation failure: Error Domain=AppleMobileFileIntegrityError Code=-413 "No matching profile found" UserInfo={NSURL=, unsatisfiedEntitlements=, NSLocalizedDescription=No matching profile found} listener failed to activate: xpc_error=[1: Operation not permitted] To resolve the profile validation failure, I registered a new App Group in the Apple Developer Portal, generated a new provisioning profile for the daemon that includes this group, and embedded it into the bundle (Contents/embedded.provisionprofile). Now, the previous profile error is gone, but I am getting a new identity conflict error, and the XPC listener still fails: Two equal instances have unequal identities. <anon<myproc_name>(501) pid=2818 AUID=501> and <anon<myproc_name>(501)(262) pid=2818 AUID=262> listener failed to activate: xpc_error=[1: Operation not permitted] My questions are: What exactly causes the Two equal instances have unequal identities error? I noticed the Audit UID difference (AUID=501 vs AUID=262). Why does NSXPCListener still fail with Operation not permitted? What is the recommended workflow for debugging a Launch Daemon that requires an App Group provisioning profile for XPC communication? Thank you in advance!
2
0
277
Apr ’26
Securing XPC Daemon Communication from Authorization Plugin
I'm working on securing communication between an Authorization Plugin and an XPC daemon, and I’d appreciate some guidance on best practices and troubleshooting. The current design which, I’ve implemented a custom Authorization Plugin for step-up authentication, which is loaded by Authorization Services at the loginwindow (inside SecurityAgent). This plugin acts as an XPC client and connects to a custom XPC daemon. Setup Details 1. XPC Daemon Runs as root (LaunchDaemon) Not sandboxed (my understanding is that root daemons typically don’t run sandboxed—please correct me if this is wrong) Mach service: com.roboInc.AuthXpcDaemon Bundle identifier: com.roboInc.OfflineAuthXpcDaemon 2. Authorization Plugin Bundle identifier: com.roboInc.AuthPlugin Loaded by SecurityAgent during login 3. Code Signing Both plugin and daemon are signed using a development certificate What I’m Trying to Achieve I want to secure the XPC communication so that: The daemon only accepts connections from trusted clients The plugin only connects to the legitimate daemon Communication is protected against unauthorized access The Issue I'm facing I attempted to validate code signatures using: SecRequirementCreateWithString SecCodeCopyGuestWithAttributes SecCodeCheckValidity However, validation consistently fails with: -67050 (errSecCSReqFailed) Could you please help here What is the recommended way to securely authenticate an Authorization Plugin (running inside SecurityAgent) to a privileged XPC daemon? Since the plugin runs inside SecurityAgent, how can the daemon reliably distinguish my plugin from other plugins? What is the correct approach to building a SecRequirement in this scenario? Any guidance, examples, or pointers would be greatly appreciated. Thanks in advance!
6
0
543
Mar ’26
FIFinderSync Extension fails to load on FIFinderSync Extension fails to load on macOS 26.3.1 (a) (25D771280a)
(! status in pluginkit, FinderSyncExtensionHost process missing) macOS Version: 26.3.1 Beta (25D771280a) Xcode Version: 16.3 (17C529) Steps to reproduce: Create a Finder Sync Extension project Build and install to /Applications Enable in System Settings → Extensions → Finder Extensions Extension shows ! in pluginkit output FinderSyncExtensionHost process never starts Context menu never appears in Finder Expected: Extension loads and context menu appears Actual: Extension marked with ! in pluginkit, no process launched pluginkit output: ! com.github.astronautJack.EasyNewFile.EasyNewFileExtension(1.0)
1
0
256
Mar ’26
Background upload issue in WatchOS
We are developing a watchOS application that records long audio sessions and uploads them to our backend in chunks (~5 MB each) using pre-signed URLs and URLSession background upload. Current behavior: While audio recording is active, uploads continue successfully even when the app is in the background. Once the recording stops, if multiple chunks (e.g., 10+) are still pending, the remaining uploads do not proceed in the background and appear to be suspended. We attempted to use WKExtendedRuntimeSession (mindfulness type) to allow sufficient time to enqueue background upload tasks, but the session is invalidated when the app goes to the background (e.g., wrist down or app inactive), which prevents reliable scheduling of uploads. Additionally, we added the entitlement: com.apple.developer.extended-runtime-session (mindfulness) in the Watch app entitlements file, but Xcode automatic signing fails with: “Provisioning profile does not include the com.apple.developer.extended-runtime-session entitlement.” It appears that the provisioning profile is not being updated to include this entitlement. Our questions: Is WKExtendedRuntimeSession (mindfulness) expected to support scheduling background URLSession uploads after the app goes to background? How should we reliably complete pending background uploads on watchOS after a long recording session ends? Is there any additional entitlement or recommended approach for this use case? Why is the extended runtime entitlement not being applied to the provisioning profile despite being added in the entitlements file? We are aiming to follow Apple-recommended practices for long-running tasks and background uploads on watchOS. Any guidance would be greatly appreciated.
2
0
410
Mar ’26
XPC Resources
XPC is the preferred inter-process communication (IPC) mechanism on Apple platforms. XPC has three APIs: The high-level NSXPCConnection API, for Objective-C and Swift The low-level Swift API, introduced with macOS 14 The low-level C API, which, while callable from all languages, works best with C-based languages General: Forums subtopic: App & System Services > Processes & Concurrency Forums tag: XPC Creating XPC services documentation NSXPCConnection class documentation Low-level API documentation XPC has extensive man pages — For the low-level API, start with the xpc man page; this is the original source for the XPC C API documentation and still contains titbits that you can’t find elsewhere. Also read the xpcservice.plist man page, which documents the property list format used by XPC services. Daemons and Services Programming Guide archived documentation WWDC 2012 Session 241 Cocoa Interprocess Communication with XPC — This is no longer available from the Apple Developer website )-: Technote 2083 Daemons and Agents — It hasn’t been updated in… well… decades, but it’s still remarkably relevant. TN3113 Testing and Debugging XPC Code With an Anonymous Listener technote XPC and App-to-App Communication forums post Validating Signature Of XPC Process forums post This forums post summarises the options for bidirectional communication This forums post explains the meaning of the privileged flag XPC is mostly used on macOS but there are a few places where it comes into play on iOS: File Provider extensions can export an XPC service to arbitrary apps. For more about the File Provider side of this, see the NSFileProviderServiceSource protocol. For more about the client side, see the NSFileProviderService class. An app can move part of its code into a helper extension and talk to it using XPC. See Creating enhanced security helper extensions. Alternative browser engines can do a similar thing. See BrowserEngineKit for more about this. Apps with embedded extensions can use XPC via ExtensionFoundation. (Note that on iOS, but not macOS, an app can only use extensions embedded within the app itself.) Related tags include: Inter-process communication, for other IPC mechanisms Service Management, for installing and uninstalling Service Management login items, launchd agents, and launchd daemons Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com"
0
0
3.7k
Mar ’26
BGProcessingTask expirationHandler — No way to distinguish expiration reason
The expirationHandler on BGProcessingTask is a () -> Void closure. It provides no information about why it was called. In my testing, all of the following trigger the same handler: Time expiration Resource pressure (CPU, memory, battery) Not reporting progress User tapping "Stop" on the Live Activity There is no way for the app to tell these apart. Questions: Q1. Is there an official, complete list of all conditions that trigger expirationHandler? The documentation only mentions "time expires." Q2. What is the specific time limit before timeout? If it varies by device state, what are the conditions? Q3. A way to distinguish the reason is needed. "User stop" and "system expiration" require completely different handling. Currently this is impossible. Environment: iOS 26, physical device
5
0
365
Mar ’26
BGProcessingTask expirationHandler — No way to distinguish expiration reason
The expirationHandler on BGProcessingTask is a () -> Void closure. It provides no information about why it was called. In my testing, all of the following trigger the same handler: Time expiration Resource pressure (CPU, memory, battery) Not reporting progress User tapping "Stop" on the Live Activity There is no way for the app to tell these apart. Questions: Q1. Is there an official, complete list of all conditions that trigger expirationHandler? The documentation only mentions "time expires." Q2. What is the specific time limit before timeout? If it varies by device state, what are the conditions? Q3. A way to distinguish the reason is needed. "User stop" and "system expiration" require completely different handling. Currently this is impossible. Environment: iOS 26, physical device
1
0
240
Mar ’26
Processes & Concurrency Resources
General: DevForums subtopic: App & System Services > Processes & Concurrency Processes & concurrency covers a number of different technologies: Background Tasks Resources Concurrency Resources — This includes Swift concurrency. Service Management Resources XPC Resources Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com"
Replies
0
Boosts
0
Views
585
Activity
Jul ’25
I want to bang my head into a brick wall
I had the issue pop up again. To refresh what previously happened, when I would submit a new build to TestFlight, it wouldn’t let me download it. That was a problem for a couple weeks. Then after the problem resolved I was able to download the “new build” but when I went into the app, it was clearly an old one. This issue got resolved a couple weeks ago, now it’s back. When I went to test out the new build on a couple of my apps, I was able to download it, but when I looked through the app, it was an old one. Please help me resolve this fast. Last time I waited for over a month
Replies
0
Boosts
0
Views
48
Activity
16h
iOS 26.5 SIGKILLs audio-recording app at ~50s of background despite UIBackgroundModes: audio - what is the supported API path?
Hi, hoping for guidance on what's a long-running bug for our app. The problem We have a transcription app on iPhone 17 Pro Max running iOS 26.5. Recording flow uses AVAudioEngine.installTap(onBus:) to capture PCM into a JS bridge for streaming to a remote transcription service. A parallel AVAudioRecorder writes the same audio to disk as backup. When the user starts a recording and locks the phone, iOS terminates our process with SIGKILL at approximately 50 seconds of continuous background time, despite: UIBackgroundModes includes audio (verified in shipping IPA's Info.plist) AVAudioSession.setCategory(.playAndRecord, mode: .default) is active AVAudioEngine is running with installTap producing PCM buffers right up to the moment of death UIApplication.backgroundTimeRemaining returns Double.greatestFiniteMagnitude at applicationDidEnterBackground (verified in our event log) No AVAudioSession.interruptionNotification is delivered before the kill. iOS terminates the process cleanly with no warning event to our observer. Evidence Our Swift observer module writes an event log to disk on every system event. On relaunch we ship it to our crash reporter. Excerpt from a recent kill on iOS 26.5 / build 2.1.32: T=0.000s session-start (engineRunning: true) T=57.199s app-will-resign-active (bufferCallbackCount: 22) T=58.913s app-did-enter-background (backgroundTimeRemaining: infinity, bufferCallbackCount: 39) [no further audio events captured] [Swift heartbeat written every 5s for next ~46 seconds] T~105s Process SIGKILLed (heartbeat last-alive: 09:31:01.597Z) Background time before kill: ~46 seconds. engineRunning: true and bufferCallbackCount was still incrementing at the moment the event log stops capturing - the audio engine was alive and feeding buffers when iOS terminated us. What we've tried (35 documented attempts) Hopefully not all relevant but listing for completeness: Various AVAudioSession category/mode/options combinations (Default, Measurement, VoiceChat, .mixWithOthers, .defaultToSpeaker, .allowBluetoothHFP) Parallel AVAudioRecorder writing a .caf file as a "real recording app" signal SFSpeechRecognizer with requiresOnDeviceRecognition = true consuming PCM in-process (50s request rotation) BGContinuedProcessingTask with Progress.completedUnitCount reporting monotonic progress every 5 seconds Live Activity (ActivityKit) with NSSupportsLiveActivitiesFrequentUpdates = true Live Activity update pushes via APNs (confirmed wake widget extension only, not host) Silent device-token APNs background pushes (confirmed iOS ~5/day rate limit) CallKit fake call (CXProvider + CXCallController) - works but creates the green pill UI which our product can't ship WebRTC peer connection with active media stream (via react-native-webrtc loopback) UIBackgroundModes: voip declaration (without CallKit) beginBackgroundTask + engine bounce (Apple's own guidance says don't, our test confirmed it's actively harmful) CLLocationManager background updates All die at ~50s background. None of them survive. What works on the same device Three App Store transcription apps survive indefinite background recording on our exact device + iOS version. We have inspected their IPAs (Mach-O LC_LOAD_DYLIB analysis + embedded entitlement extraction): Otter (com.aisense.otter) - UIBackgroundModes: audio + fetch + processing + remote-notification. Uses OneSignal-driven Live Activity push tokens + NotificationServiceExtension. No CallKit, PushKit, or WebRTC. Granola (com.granola.ios-prod) - has UIBackgroundModes: voip but the voip is for their separate outbound-phone-call feature (TwilioVoice + CallKit, lives in their PhoneCalls.framework). Recording-path uses ONLY AVAudioRecorder + PlayAndRecord + ModeDefault + Live Activity with frequentPushesEnabled. Zero PushKit anywhere in the bundle. Transcribe Speech to Text by DENIVIP (ru.denivip.transcribe) - the smallest API surface: UIBackgroundModes: audio + remote-notification only. AVAudioEngine + .playAndRecord + .default + SFSpeechRecognizer consuming PCM. No CallKit, PushKit, BGTask, Live Activity, WebRTC, or VoIP. Three apps, three different mechanisms, all working. We've implemented bits of all three approaches in our app and still die at 50s. Apple Voice Memos (system app, private entitlements) also survives indefinite recording on the same device. Questions What is the supported API path for indefinite background microphone-only recording on iOS 26.5? Voice Memos and competitor apps clearly accomplish this - what's the missing piece? Why does UIApplication.backgroundTimeRemaining return Double.greatestFiniteMagnitude at applicationDidEnterBackground but the process is terminated ~50 seconds later? Is the meaning of this property changing in iOS 26? What causes the iOS 26 process scheduler to revoke the audio-mode background runtime classification? No AVAudioSession.interruptionNotification is delivered before SIGKILL. Where can we observe the classification change? Does iOS 26 distinguish "audio recording with no audible output" from "audio recording with audible output (e.g. a media playback session)"? If so, what is the supported API to register as a recording-only background-audio app? Does BGContinuedProcessingTask (new in iOS 26) actually extend background CPU time for an app that is also using UIBackgroundModes: audio and an active AVAudioSession? Or is it for finish-what-you-started bursts only (per WWDC 2025 session 227)? Any guidance - even pointers to specific WWDC sessions, sample code, or technotes - would be hugely appreciated. We've spent ~40+ hours on this and want to know what the supported path looks like in iOS 26. Happy to share more event-log data, IPA inspection notes, or build a focused Xcode reproduction if helpful. Thanks!
Replies
1
Boosts
0
Views
126
Activity
3d
iPadOS 26.4+ significantly reduced per-app memory limit from 6GB to 3GB on 8GB iPad, breaking memory-intensive apps
Summary: Starting from iPadOS 26.4, the maximum memory available to a single app has been reduced from approximately 6GB to 3GB on an 8GB iPad. This change persists in iPadOS 26.5 and has not been addressed. This breaks core functionality of memory-intensive applications such as 3D scanning apps that require large amounts of RAM to process models. Device: iPad with 8GB RAM Affected versions: iPadOS 26.4, iPadOS 26.5 Working version: iPadOS 26.0 / 26.1 / 26.2 / 26.3 Measured Data: iPadOS 26.0–26.3: App available memory ≈ 6GB (75% of total RAM) iPadOS 26.4–26.5: App available memory ≈ 3GB (37.5% of total RAM) Measurement method: Apple system API Impact: This is a regression, not expected behavior. The available memory per app has been cut by 50% without any official documentation or release notes mentioning this change. As a result, our 3D scanning application crashes immediately when attempting to process 3D models on iPadOS 26.4 and later. The app requires substantial RAM to load and process 3D model data. With only 3GB available, memory allocation fails during model processing, causing the app to crash (EXC_RESOURCE / OOM kill). This core functionality was working correctly on iPadOS 26.3 and earlier with the same device and same app binary. This regression makes our app's primary feature completely unusable for all users on iPadOS 26.4+. Steps to Reproduce: On an 8GB iPad, install iPadOS 26.0 Measure available app memory using Apple system API Upgrade to iPadOS 26.4 or 26.5 Measure available app memory again Observe: available memory drops from ~6GB to ~3GB Expected Result: Available memory per app should remain consistent across minor OS updates, or any changes should be documented. Actual Result: Available memory per app dropped by 50% starting in iPadOS 26.4, with no documentation of this change. Additional Notes: Disabling Apple Intelligence does not resolve the issue This issue was not fixed in iPadOS 26.5 Other developers have reported increased crash rates starting in iPadOS 26.4 (Apple Developer Forums)
Replies
1
Boosts
0
Views
109
Activity
4d
XPC Communication between Editor app and user-compiled code
Hello! I'm trying to implement an editor app (macOS) that allows the user to write code, which will be compiled and executed, showing the result in the editor window. Imagine it like SwiftUI previews, but the graphic output is created with Metal, not SwiftUI. I found that IOSurface can be used to share that kind of data over XPC, so I would not have to rely on the private NSRemoteView. However, I'm confused if it is, at all, possible for my editor app to connect to an XPC Service, that was NOT bundled with it (but compiled by it at runtime). I succeeded to launch an XPC service defined as: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>Label</key> <string>com.myteam.myproject.service</string> <key>MachServices</key> <dict> <key>com.myteam.myproject.service</key> <true/> </dict> <key>Program</key> <string>/Path/to/service/run_my_service.sh</string> </dict> </plist> But the call to let connection = NSXPCConnection(machServiceName: "com.myteam.myproject.service") let proxy = connection.remoteObjectProxyWithErrorHandler { error in continuation.resume(throwing: error) } as? MyServiceProtocol fails with "The connection to service named com.myteam.myproject.service was invalidated: Connection init failed at lookup with error 3 - No such process." I have added <key>com.apple.security.temporary-exception.mach-lookup.global-name</key> <array> <string>com.myteam.myproject.service</string> </array> to my entitlements. Since the tutorials I followed are quite old, I'm wondering if support for something like this was dropped at some point. Thanks for any advice!
Replies
6
Boosts
0
Views
425
Activity
5d
iOS feasibility question: user-initiated wake-word detection during active session
Hi all, Technical architecture question for those experienced with iOS background audio / microphone constraints. I’m exploring an app concept where: the user explicitly starts a temporary active session during that session, on-device wake-word / keyword detection runs locally no audio is stored or transmitted during passive monitoring monitoring stops when the user ends the session The intended UX is that the user may then lock the phone or place it away while the active session remains in progress. Question: Is there any App Store-compliant architecture that would allow local keyword / wake-word detection to continue while the device is locked or the app is backgrounded during that active session? Or would iOS lifecycle / background execution rules make this infeasible for custom wake-word detection? Interested in practical experience around: AVAudioSession background audio modes on-device speech processing App Review acceptability Thanks in advance.
Replies
0
Boosts
0
Views
192
Activity
5d
SMAppService - helper is not started
My software installs a privileged daemon using the SMAppService api. After removing the executables and recompiling the software I sometimes find that it needs to be registered again. After doing this, i.e. ensuring the application is properly registered and enabled in Login Items & Extensions the helper is not run when initiated from XPC. SMAppService.status has returned .enabled, and there is a valid job dictionary for the helper. I check the job dictionary with a function called updatePenaltyBoxStatus() that was given to me by a friend but I think originated from Apple. If I logoff (or reboot), login again, manually open Login Items & Extensions to check registration, then retry the application, it works. I don't mind doing this but it is probably a bit much for a lot of my users. Is there a reliable way to do this programatically? Here is my Swift translation of updatePenaltyBoxStatus. I fetch the job dictionary with SMJobCopyDictionary() prior to calling isInPenaltyBox(). I also had to write C wrapper functions for the WIFEXITED and WIFEXITSTATUS macros. func isInPenaltyBox(_ dict: Dictionary<String, Any>?) -> Bool { guard let jobDict = dict else { // If the helper was in the penalty box, unregistering it doesn't change that. So don't override a previous helperInPenaltyBox value return m_penalty_box } if let lastExitStatusObj = jobDict["LastExitStatus"] as? NSNumber { let lastExitStatus = lastExitStatusObj.intValue if wifexited(Int32(lastExitStatus)) == 0 { // It might've stopped or exited due to a signal or whatever. // Regardless, it didn't meet our criteria for winding up in the penalty box. m_penalty_box = false } // Now get the exit status and check for `EX_CONFIG`. let status = wexitstatus(Int32(lastExitStatus)) let newInPenaltyBox = status == EX_CONFIG if m_penalty_box != newInPenaltyBox { Logger.instance.log( "Penalty box change: " + m_ident + " old: " + String(m_penalty_box) + " new: " + String(newInPenaltyBox)) } m_penalty_box = newInPenaltyBox } return m_penalty_box }
Replies
2
Boosts
0
Views
259
Activity
2w
Background Assets: Downloaded .aar not working — "bundle record couldn't be looked up" error (-10814)
Platform: iOS 26 (23E254) Xcode: 26.0 Reproduces on: Debug builds AND TestFlight Summary: I'm using Apple-Hosted Managed Background Assets with on-demand download policy. The .aar archives download successfully (correct file size, status = downloaded), but the contents are never extracted into the asset pack namespace. AssetPackManager.shared.contents(at:) returns fileNotFound for all path variants, and url(for: FilePath(".")) returns a URL that exists but contains zero children. Root Cause from Sysdiagnose: The backgroundassets.user daemon logs reveal this error on every download attempt: A bundle record couldn't be looked up for the application identifier "AtlasDrift.SnapTrail": Error Domain=NSOSStatusErrorDomain Code=-10814 "(null)" UserInfo={_LSFile=LSBindingEvaluator.mm, _LSLine=1973, _LSFunction=runEvaluator} Error code -10814 is kLSApplicationNotFoundErr. The BA daemon downloads the .aar blob, then attempts to find the app bundle via LaunchServices to locate the extension for extraction — but the LS lookup fails. Without the extension, extraction never occurs. Verified Configuration Everything matches the documentation and WWDC sessions: Extension embedded at SnapTrail.app/Extensions/BackgroundDownloadExtension.appex Bundle IDs: App = AtlasDrift.SnapTrail, Extension = AtlasDrift.SnapTrail.BackgroundDownloadExtension (correct parent-child pattern) Extension point: com.apple.background-asset-downloader-extension Product type: com.apple.product-type.extensionkit-extension Protocol: StoreDownloaderExtension from StoreKit (for Apple-hosted packs) App group: group.AtlasDrift.SnapTrail (matching in both app and extension entitlements) Info.plist keys: BAAppGroupID, BAHasManagedAssetPacks = YES BAUsesAppleHosting = YES (no BAInitialDownloadRestrictions or other BA keys) .aar Packaging Archives built with xcrun ba-package from the Assets directory. Manifest format: { "assetPackID": "ireland", "downloadPolicy": { "onDemand": {} }, "fileSelectors": [{ "directory": "POIRegions/ireland/IR" }], "platforms": ["iOS"] } Uploaded via App Store Connect API with assetType: "ASSET". Diagnostic Observations AssetPackManager.shared.assetPack(withID:) returns valid metadata (correct download size) ensureLocalAvailability(of:) completes without error assetPackIsAvailableLocally(withID:) returns true url(for: FilePath(".")) returns a URL that exists but has zero children (empty namespace) contents(at:) returns fileNotFound for all path variants tested The extension never runs — breadcrumb file written in init() is never created The -10814 error appears in daemon logs for every download cycle Questions Has anyone successfully used Apple-Hosted Managed Background Assets on iOS 26 beta? Is the daemon's LaunchServices integration known to be broken in this seed? Is there anything about the bundle identifier format or provisioning profile setup that could cause the BA daemon's LS lookup to fail, even though the app installs and runs fine otherwise? Are there any additional Info.plist keys or entitlements beyond what's documented that might be required for the daemon to locate the app bundle? Any guidance would be appreciated. I've filed a Feedback report with the full sysdiagnose attached.
Replies
1
Boosts
0
Views
240
Activity
2w
applicationWillTerminate to wrap up Background Recording
Hello together, the user is able to do recordings with my app. The recordings also runs, while the App is in Background. I have Background Modes Audio & Background enabled. When the user accidentally terminates the App while the recording is still running, the whole recording is lost. I tried AppDelegate applicationWillTerminate on my iOS 26 App and it works perfectly to wrap up the LiveActivity that is shown while the recording is active. But it does not save the Audio and also doesn't update the Widgets (they are interactive and show a different state while recording and stay stuck in recording-state on accidental termination). Any ideas? Best wishes, Dominik
Replies
2
Boosts
0
Views
223
Activity
2w
Safari web extensions: Optimal IPC architecture between extension and the containing app
I'm building a macOS safari extension and porting its functionality from a chrome extension. The chrome extension uses native messaging hosts to communicate with another process using IPC and holding a persistent connection. To use the same functionality in Safari, I understand that will need to use the handler to communicate it to the containing app, and the app will have to hold the persistent IPC connection. My question derives from that concept: should the app be running in a long-lived state? And if so, how can I ensure that app be running 100% of the time. Also is there any way I can control it's lifecycle with the Safari browser's lifecycle? I will not be using XPC here, but a different UDS to make the connection. Also in addition to that, what would you recommend the best approach is the communicate between the extension and it's handler? -> should it be again a UDS or userDefaults +darwin notification be enough? Also I wouldn't want the inter-message relayed between components to be dropped, is there a fault tolerant architecture you would recommend?
Replies
0
Boosts
0
Views
178
Activity
3w
Unable to set subtitle when BGContinuedProcessingTask expires
Hi, I've now identified a few areas when BGContinuedProcessingTask gets expired by the system no progress for ~30 seconds high CPU usage high temperature Some of these I can preempt and expire preemptively and handle the notification, others I cannot and just need to let the failure bubble up. When the failure does bubble up, I'd like to update the title and subtitle. I'm able to update the title, but the subtitle is fixed at "Task Failed" Is there any workaround? Or shall I file a bug here?
Replies
1
Boosts
0
Views
357
Activity
Apr ’26
Best practice for replacing deprecated sem_init/sem_wait in a cross-platform threading layer on macOS (arm64)
Hi all, I'm working on a cross-platform runtime that manages a pool of threads (think game engine / emulator style... dozens of guest threads mapped 1:1 to host pthreads). It was originally written for Linux and Windows and we're now porting to macOS on Apple Silicon. We've hit a wall with a deadlock on macOS and traced it back to our use of POSIX unnamed semaphores (sem_init / sem_wait / sem_post) for thread suspend and resume. We were unaware these have never actually been implemented on macOS, sem_init silently returns -1 with ENOSYS and then sem_wait just hangs forever. That explains our deadlock. The tricky part is how we use them. Our suspend mechanism works by sending SIGUSR1 to a target thread via pthread_kill. The signal handler then calls sem_wait to block the thread in place until another thread calls sem_post to resume it. So whatever we replace sem_init/sem_wait with needs to be safe to call from inside a signal handler. From what I can tell: dispatch_semaphore_wait is not documented as async-signal-safe pthread_cond_wait is also not async-signal-safe os_sync_wait_on_address looks promising but requires macOS 14.4+ which is a pretty high floor We could spin on a std::atomic with .wait() / .notify_all() but I've seen reports of high wake latency (up to 15ms) in libc++'s implementation on macOS My questions: What's the recommended way to block a thread inside a signal handler on macOS? Is there an async-signal-safe wait primitive I'm missing? Would restructuring to avoid blocking in the signal handler entirely be the better approach? For example, having the signal handler just set an atomic flag and then checking it at yield points — would that be the expected pattern on macOS? For the non-signal-handler suspend/resume paths, is dispatch_semaphore_t the right replacement for sem_t, or is there something better suited for high-frequency thread synchronization in 2026? Separately, we're also using ucontext (makecontext/swapcontext) for a fiber system on macOS and hitting issues on native arm64, it works under Rosetta but breaks natively. We have a setjmp/longjmp + manual stack pivot backend we can switch to. Is there any plan to fix or un-deprecate the ucontext functions on arm64, or should we just move off them permanently?
Replies
2
Boosts
0
Views
204
Activity
Apr ’26
iOS: Issues getting beginBackgroundTaskWithName working reliably
We have tried using background tasks for file saving via (UIBackgroundTaskIdentifier) beginBackgroundTaskWithName:(NSString *) taskName expirationHandler:(void (^)(void)) handler; when our app goes into the background and/or is closed by the user. But we cannot make it work the way the documentation tells us it should. While task creation never reports an issue (in fact it never calls our expiration handler at all) and the returned task id is always valid, when we ask for how much time we have left via backgroundTimeRemaining we always get 6s instead of the specified 30s. We tried to create the task when the app state goes to inactive or when our delegate is called via applicationDidEnterBackground but it makes no difference, besides the fact that the remaining time reported is basically max double, when the app is not in background yet which is by design as far we understand. But we don't even get the 6s for saving when a user closes the app. Because almost immediately after applicationDidEnterBackground our delegate is called via applicationWillTerminate which will then again almost immediately end in the app receiving a SIGKILL. So we must be doing something wrong. Why would applicationWillTerminate be called at all when we have a valid background task that reports we have 6s left? We tried blocking the thread in both background and terminate to at least give us the 5s the spec says we have before we get the SIGKILL. That works in general but doesn't feel like the correct approach and we do need more time than the 5s or 6s we get this way. Are we supposed to add something to our plist in order for these background tasks to work correctly? It is very confusing that there is a second mechanism that's also called background tasks for running apps in the background in general, which is not applicable to us. Are we supposed to block somewhere when we create the task? Or even spin up an extra thread for the task? Why is our expirationHandler never called? The spec says that our handler should be called if it was unable to "grant the ask assertion" so it seems like we do not have that problem. But it's also supposed to be called just before we are running out of time but by that time the app is already dead. This was all tested on iOS 26.3 and it is probably worth mentioning that our app is Qt-based.
Replies
4
Boosts
0
Views
266
Activity
Apr ’26
how to get process exec event
Besides using esf, are there any other ways to perceive process start events in real time? Libbsm is currently disabled by default
Replies
1
Boosts
0
Views
175
Activity
Apr ’26
How to debug a Launch Daemon that requires an App Group provisioning profile for XPC communication
Hello, I am developing a macOS Launch Daemon (packaged as a bundle) that acts as an XPC server. For debugging purposes, I am trying to run the daemon's executable directly from the terminal via sudo ./mydaemon.app/Contents/MacOS/myexecutable. Initially, I added the com.apple.security.application-groups entitlement to the daemon. However, when starting the process, it failed to create the XPC service with the following errors: Unsatisfied entitlements: com.apple.security.application-groups Soft-restriction provisioning profile validation failure: Error Domain=AppleMobileFileIntegrityError Code=-413 "No matching profile found" UserInfo={NSURL=, unsatisfiedEntitlements=, NSLocalizedDescription=No matching profile found} listener failed to activate: xpc_error=[1: Operation not permitted] To resolve the profile validation failure, I registered a new App Group in the Apple Developer Portal, generated a new provisioning profile for the daemon that includes this group, and embedded it into the bundle (Contents/embedded.provisionprofile). Now, the previous profile error is gone, but I am getting a new identity conflict error, and the XPC listener still fails: Two equal instances have unequal identities. <anon<myproc_name>(501) pid=2818 AUID=501> and <anon<myproc_name>(501)(262) pid=2818 AUID=262> listener failed to activate: xpc_error=[1: Operation not permitted] My questions are: What exactly causes the Two equal instances have unequal identities error? I noticed the Audit UID difference (AUID=501 vs AUID=262). Why does NSXPCListener still fail with Operation not permitted? What is the recommended workflow for debugging a Launch Daemon that requires an App Group provisioning profile for XPC communication? Thank you in advance!
Replies
2
Boosts
0
Views
277
Activity
Apr ’26
Securing XPC Daemon Communication from Authorization Plugin
I'm working on securing communication between an Authorization Plugin and an XPC daemon, and I’d appreciate some guidance on best practices and troubleshooting. The current design which, I’ve implemented a custom Authorization Plugin for step-up authentication, which is loaded by Authorization Services at the loginwindow (inside SecurityAgent). This plugin acts as an XPC client and connects to a custom XPC daemon. Setup Details 1. XPC Daemon Runs as root (LaunchDaemon) Not sandboxed (my understanding is that root daemons typically don’t run sandboxed—please correct me if this is wrong) Mach service: com.roboInc.AuthXpcDaemon Bundle identifier: com.roboInc.OfflineAuthXpcDaemon 2. Authorization Plugin Bundle identifier: com.roboInc.AuthPlugin Loaded by SecurityAgent during login 3. Code Signing Both plugin and daemon are signed using a development certificate What I’m Trying to Achieve I want to secure the XPC communication so that: The daemon only accepts connections from trusted clients The plugin only connects to the legitimate daemon Communication is protected against unauthorized access The Issue I'm facing I attempted to validate code signatures using: SecRequirementCreateWithString SecCodeCopyGuestWithAttributes SecCodeCheckValidity However, validation consistently fails with: -67050 (errSecCSReqFailed) Could you please help here What is the recommended way to securely authenticate an Authorization Plugin (running inside SecurityAgent) to a privileged XPC daemon? Since the plugin runs inside SecurityAgent, how can the daemon reliably distinguish my plugin from other plugins? What is the correct approach to building a SecRequirement in this scenario? Any guidance, examples, or pointers would be greatly appreciated. Thanks in advance!
Replies
6
Boosts
0
Views
543
Activity
Mar ’26
FIFinderSync Extension fails to load on FIFinderSync Extension fails to load on macOS 26.3.1 (a) (25D771280a)
(! status in pluginkit, FinderSyncExtensionHost process missing) macOS Version: 26.3.1 Beta (25D771280a) Xcode Version: 16.3 (17C529) Steps to reproduce: Create a Finder Sync Extension project Build and install to /Applications Enable in System Settings → Extensions → Finder Extensions Extension shows ! in pluginkit output FinderSyncExtensionHost process never starts Context menu never appears in Finder Expected: Extension loads and context menu appears Actual: Extension marked with ! in pluginkit, no process launched pluginkit output: ! com.github.astronautJack.EasyNewFile.EasyNewFileExtension(1.0)
Replies
1
Boosts
0
Views
256
Activity
Mar ’26
Background upload issue in WatchOS
We are developing a watchOS application that records long audio sessions and uploads them to our backend in chunks (~5 MB each) using pre-signed URLs and URLSession background upload. Current behavior: While audio recording is active, uploads continue successfully even when the app is in the background. Once the recording stops, if multiple chunks (e.g., 10+) are still pending, the remaining uploads do not proceed in the background and appear to be suspended. We attempted to use WKExtendedRuntimeSession (mindfulness type) to allow sufficient time to enqueue background upload tasks, but the session is invalidated when the app goes to the background (e.g., wrist down or app inactive), which prevents reliable scheduling of uploads. Additionally, we added the entitlement: com.apple.developer.extended-runtime-session (mindfulness) in the Watch app entitlements file, but Xcode automatic signing fails with: “Provisioning profile does not include the com.apple.developer.extended-runtime-session entitlement.” It appears that the provisioning profile is not being updated to include this entitlement. Our questions: Is WKExtendedRuntimeSession (mindfulness) expected to support scheduling background URLSession uploads after the app goes to background? How should we reliably complete pending background uploads on watchOS after a long recording session ends? Is there any additional entitlement or recommended approach for this use case? Why is the extended runtime entitlement not being applied to the provisioning profile despite being added in the entitlements file? We are aiming to follow Apple-recommended practices for long-running tasks and background uploads on watchOS. Any guidance would be greatly appreciated.
Replies
2
Boosts
0
Views
410
Activity
Mar ’26
XPC Resources
XPC is the preferred inter-process communication (IPC) mechanism on Apple platforms. XPC has three APIs: The high-level NSXPCConnection API, for Objective-C and Swift The low-level Swift API, introduced with macOS 14 The low-level C API, which, while callable from all languages, works best with C-based languages General: Forums subtopic: App & System Services > Processes & Concurrency Forums tag: XPC Creating XPC services documentation NSXPCConnection class documentation Low-level API documentation XPC has extensive man pages — For the low-level API, start with the xpc man page; this is the original source for the XPC C API documentation and still contains titbits that you can’t find elsewhere. Also read the xpcservice.plist man page, which documents the property list format used by XPC services. Daemons and Services Programming Guide archived documentation WWDC 2012 Session 241 Cocoa Interprocess Communication with XPC — This is no longer available from the Apple Developer website )-: Technote 2083 Daemons and Agents — It hasn’t been updated in… well… decades, but it’s still remarkably relevant. TN3113 Testing and Debugging XPC Code With an Anonymous Listener technote XPC and App-to-App Communication forums post Validating Signature Of XPC Process forums post This forums post summarises the options for bidirectional communication This forums post explains the meaning of the privileged flag XPC is mostly used on macOS but there are a few places where it comes into play on iOS: File Provider extensions can export an XPC service to arbitrary apps. For more about the File Provider side of this, see the NSFileProviderServiceSource protocol. For more about the client side, see the NSFileProviderService class. An app can move part of its code into a helper extension and talk to it using XPC. See Creating enhanced security helper extensions. Alternative browser engines can do a similar thing. See BrowserEngineKit for more about this. Apps with embedded extensions can use XPC via ExtensionFoundation. (Note that on iOS, but not macOS, an app can only use extensions embedded within the app itself.) Related tags include: Inter-process communication, for other IPC mechanisms Service Management, for installing and uninstalling Service Management login items, launchd agents, and launchd daemons Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com"
Replies
0
Boosts
0
Views
3.7k
Activity
Mar ’26
BGProcessingTask expirationHandler — No way to distinguish expiration reason
The expirationHandler on BGProcessingTask is a () -> Void closure. It provides no information about why it was called. In my testing, all of the following trigger the same handler: Time expiration Resource pressure (CPU, memory, battery) Not reporting progress User tapping "Stop" on the Live Activity There is no way for the app to tell these apart. Questions: Q1. Is there an official, complete list of all conditions that trigger expirationHandler? The documentation only mentions "time expires." Q2. What is the specific time limit before timeout? If it varies by device state, what are the conditions? Q3. A way to distinguish the reason is needed. "User stop" and "system expiration" require completely different handling. Currently this is impossible. Environment: iOS 26, physical device
Replies
5
Boosts
0
Views
365
Activity
Mar ’26
BGProcessingTask expirationHandler — No way to distinguish expiration reason
The expirationHandler on BGProcessingTask is a () -> Void closure. It provides no information about why it was called. In my testing, all of the following trigger the same handler: Time expiration Resource pressure (CPU, memory, battery) Not reporting progress User tapping "Stop" on the Live Activity There is no way for the app to tell these apart. Questions: Q1. Is there an official, complete list of all conditions that trigger expirationHandler? The documentation only mentions "time expires." Q2. What is the specific time limit before timeout? If it varies by device state, what are the conditions? Q3. A way to distinguish the reason is needed. "User stop" and "system expiration" require completely different handling. Currently this is impossible. Environment: iOS 26, physical device
Replies
1
Boosts
0
Views
240
Activity
Mar ’26