General: DevForums subtopic: App & System Services > Core OS Core OS is a catch-all subtopic for low-level APIs that don’t fall into one of these more specific areas: Processes & Concurrency Resources Files and Storage Resources Networking Resources Network Extension Resources Security Resources Virtualization Resources Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com"

On a MacBook Pro, 16GB of RAM, 500 GB SSD, OS Sequoia 15.7.1, M3 chip, I am running some python3 code in a conda environment that requires lots of RAM and sure enough, once physical memory is almost exhausted, swapfiles of about 1GB each start being created, which I can see in /System/Volumes/VM. This folder has about 470 GB of available space at the start of the process (I can see this through get info) however, once about 40 or so swapfiles are created, for a total of about 40GB of virtual memory occupied (and thus still plenty of available space in VM), zsh kills the python process responsible for the RAM usage (notably, it does not kill another python process using only about 100 MB of RAM). The message received is "zsh: killed" in the tmux pane where the logging of the process is printed. All the documentation I was able to consult says that macOS is designed to use up to all available storage on the startup disk (which is the one I am using since I have only one disk and the available space aforementioned reflects this) for swapping, when physical RAM is not enough. Then why is the process killed long before the swapping area is exhausted? In contrast, the same process on a Linux machine (basic python venv here) just keeps swapping, and never gets killed until swap area is exhausted. One last note, I do not have administrator rights on this device, so I could not run dmesg to retrieve more precise information, I can only check with df -h how the swap area increases little by little. My employer's IT team confirmed that they do not mess with memory usage on managed profiles, so macOS is just doing its thing. Thanks for any insight you can share on this issue, is it a known bug (perhaps with conda/python environments) or is it expected behaviour? Is there a way to keep the process from being killed?

I can reproduce the bug that CallKit doesn't active audiosession after the outgoing call put on hold because of an incoming call. VoIP calling with CallKit Steps to reproduce: Download SpeakerBox example app from the link above and start it with XCode Start a new outgoing call Call your phone from other phone Hold and Accept the call After a few secs finish the call from the other phone The outgoing call will be still on hold Click on the call and click Toggle Hold The call won't be active again because the audiosession is activated. Logs: Received provider(_:didDeactivate:) Received provider(_:didDeactivate:) Received provider(_:didDeactivate:) Received provider(_:didDeactivate:) Received provider(_:didDeactivate:) Requested transaction successfully Starting audio Type: stdio AURemoteIO.cpp:1162 failed: 561017449 (enable 3, outf< 1 ch, 44100 Hz, Float32> inf< 1 ch, 44100 Hz, Float32>) Type: Error | Timestamp: 2024-08-15 12:20:29.949437+02:00 | Process: Speakerbox | Library: libEmbeddedSystemAUs.dylib | Subsystem: com.apple.coreaudio | Category: aurioc | TID: 0x19540d AVAEInternal.h:109 [AVAudioEngineGraph.mm:1344:Initialize: (err = PerformCommand(*outputNode, kAUInitialize, NULL, 0)): error 561017449 Type: Error | Timestamp: 2024-08-15 12:20:29.949619+02:00 | Process: Speakerbox | Library: AVFAudio | Subsystem: com.apple.avfaudio | Category: avae | TID: 0x19540d Couldn't start Apple Voice Processing IO: Error Domain=com.apple.coreaudio.avfaudio Code=561017449 "(null)" UserInfo={failed call=err = PerformCommand(*outputNode, kAUInitialize, NULL, 0)} Type: Notice | Timestamp: 2024-08-15 12:20:29.949730+02:00 | Process: Speakerbox | Library: Speakerbox | TID: 0x19540d Route change: Type: Notice | Timestamp: 2024-08-15 12:20:30.167498+02:00 | Process: Speakerbox | Library: Speakerbox | TID: 0x19540d ReasonUnknown Type: Notice | Timestamp: 2024-08-15 12:20:30.167549+02:00 | Process: Speakerbox | Library: Speakerbox | TID: 0x19540d Previous route: Type: Notice | Timestamp: 2024-08-15 12:20:30.167568+02:00 | Process: Speakerbox | Library: Speakerbox | TID: 0x19540d <AVAudioSessionRouteDescription: 0x302c00bc0, inputs = ( "<AVAudioSessionPortDescription: 0x302c01330, type = MicrophoneBuiltIn; name = iPhone Mikrofon; UID = Built-In Microphone; selectedDataSource = (null)>" ); outputs = ( "<AVAudioSessionPortDescription: 0x302c004d0, type = Receiver; name = Vev\U0151; UID = Built-In Receiver; selectedDataSource = (null)>" )> Type: Notice | Timestamp: 2024-08-15 12:20:30.167626+02:00 | Process: Speakerbox | Library: Speakerbox | TID: 0x19540d

A user of one of my apps reported that since the update to macOS 26.1 they are no longer able to scan Macintosh HD: the app used to work, but now always reports that Macintosh HD contains a single empty file named .nofollow, or rather the path is resolved to /.nofollow. Initially I thought this could be related to resolving the file from the saved bookmark data, but even restarting the app and selecting Macintosh HD in an open panel (without resolving the bookmark data) produces the same result. The user tried another app of mine with the same issue, but said that they were able to scan Macintosh HD in other App Store apps. I never heard of this issue before and my apps have been on the App Store for many years, but it looks like I might be doing something wrong, or the APIs that I use are somehow broken. In all my apps I currently use getattrlistbulk because I need attributes that are not available as URLResourceKey in all supported operating system versions. What could be the issue? I'm on macOS 26.1 myself and never experienced it.

I just saw another post regarding bookmarks on iOS where an Apple engineer made the following statement: [quote='855165022, DTS Engineer, /thread/797469?answerId=855165022#855165022'] macOS is better at enforcing the "right" behavior, so code that works there will generally work on iOS. [/quote] So I went back to my macOS code to double-check. Sure enough, the following statement: let bookmark = try url.bookmarkData(options: .withSecurityScope) fails 100% of the time. I had seen earlier statements from other DTS Engineers recommending that any use of a URL be bracketed by start/stopAccessingSecurityScopedResource. And that makes a lot of sense. If "start" returns true, then call stop. But if start returns false, then it isn't needed, so don't call stop. No harm, no foul. But what's confusing is this other, directly-related API where a security-scoped bookmark cannot be created under any circumstances because of the URL itself, some specific way the URL was initially created, and/or manipulated? So, what I'm asking is if someone could elaborate on what would cause a failure to create a security-scoped bookmark? What kinds of URLs are valid for creation of security-scoped bookmarks? Are there operations on a URL that will then cause a failure to create a security-scoped bookmark? Is it allowed to pass the URL and/or bookmark back and forth between Objective-C and Swift? I'm developing a new macOS app for release in the Mac App Store. I'm initially getting my URL from an NSOpenPanel. Then I store it in a SQLite database. I may access the URL again, after a restart, or after a year. I have a login item that also needs to read the database and access the URL. I have additional complications as well, but they don't really matter. Before I get to any of that, I get a whole volume URL from an NSOpen panel in Swift, then, almost immediately, attempt to create a security-scoped bookmark. I cannot. I've tried many different combinations of options and flows of operation, but obviously not all. I think this started happening with macOS 26, but that doesn't really matter. If this is new behaviour in macOS 26, then I must live with it. My particular use requires a URL to a whole volume. Because of this, I don't actually seem to need a security-scoped bookmark at all. So I think I might simply get lucky for now. But this still bothers me. I don't really like being lucky. I'd rather be right. I have other apps in development where this could be a bigger problem. It seems like I will need completely separate URL handling logic based on the type of URL the user selects. And what of document-scoped URLs? This experience seems to strongly indicate that security-scoped URLs should only ever be document-scoped. I think in some of my debugging efforts I tried document-scoped URLs. They didn't fix the problem, but they seemed to make the entire process more straightforward and transparent. Can a single metadata-hosting file host multiple security-scoped bookmarks? Or should I have a separate one for each bookmark? But the essence of my question is that this is supposed to be simple operation that, in certain cases, is a guaranteed failure. There are a mind-bogglingly large number of potential options and logic flows. Does there exist a set of options and logic flows for which the user can select a URL, any URL, with the explicit intent to persist it, and that my app can save, share with helper apps, and have it all work normally after restart?

We attempted to run a burn-in test while connected to our MacBook Pro M4 Max, but this crashed about 10 minutes into testing. Can Action Star see if you are able to run a 2-hour burn-in on your own M4 Max host while charging the battery from below 5%, running six bus-powered drives (via ATTO/Black Magic/IOmeter), hitting the RJ45 port for 2.5Gbps (via JPerf), and streaming at least 4K60Hz video content to two displays? Please measure the outer temperature on the hottest part of the enclosure as well.

I'm trying to test the update process for an app containing an FSKit module that I'm distributing on the Mac App Store. (I'm also distributing the same app directly with Developer ID, but here I'll focus on App Store because that's the behavior I've been looking at first.) To do that I'm using an internal tester group on TestFlight and then testing an update with TestFlight. Below is the behavior I'm seeing on macOS 15.7.2 (24G325). I've noticed that if an app update is triggered while a disk is mounted using the FSKit extension, the disk is automatically unmounted without warning (FB21287341). That's already undesirable itself in my opinion, but on top of the unmount, there are two other problems: That unmount doesn't seem to be a "clean" unmount and doesn't call functions like synchronize (FB21287688). Now, in my case, my app only provides read-only access, so that doesn't actually matter much in my case. However, I'd imagine if I were to add write access at some point in the future, this would go from "doesn't matter" to "very bad." I've seen a few cases where quitting or crashing the FSModule process while a volume is mounted without actually doing a clean unmount causes a lot of "disk-related actions" (for lack of a better term) to freeze (FB21305906). For example, a use of the mount(8) command or trying to mount a disk at all freezes, and opening Disk Utility stalls on a "Loading disks" spinning indicator. This happens until the Mac is rebooted. I did notice this issue once while testing updates via TestFlight a few times. The same applies if I simply delete the app with Finder instead of updating it. Is there a way to prevent the extension's process from terminating in this case and/or another workaround I could use without waiting for a macOS update to hopefully change this behavior? And does observing this kind of behavior with TestFlight's update behavior suggest the same thing could happen on the App Store with its automatic updates? I'm concerned that pushing an update via the App Store will unexpectedly unmount disks or cause the system-wide issues described in FB21305906 at a random time, which is a pretty big disruption for users.

If I have two iOS apps, with bundle ids com.mycompany.A and com.mycompany.B, and they both have the shared group id of group.com.mycompany.B, then they can read/write data to same file (in shared defaults or, for example, a Realm database saved to the same shared group location). What I have noticed is that if both apps get installed and some data X written to shared defaults (but data which isn't accessed by both apps i.e. if only app A uses this data), then if app A is deleted and reinstalled then X is not deleted in this situation (unless both apps A and B are deleted). I guess that is to be expected as they both use the same group id and the OS won't clear that area out unless both apps are deleted. However I think I am seeing a situation where if app A has group.com.mycompany.A as its group and app B has group.com.mycompany.B as its group, then this is still the same situation - data written by app B for doesn't get deleted if only app B is deleted/reinstalled on the phone. It won't get deleted unless both app B and A are deleted from the phone. This is not what I was expecting. I need to perform some more checks (its more complex to verify as app A is developed by one company and app B by another), but if this were to be the case would this be unexpected behavior by the OS? Presumably it would be unexpected as the container should be identified by the full group id and not a partial portion of the group id right?

Does Bluetooth work in the background in iOS 26?

We attempted to run a burn-in test while connected to our MacBook Pro M4 Max, but this crashed about 10 minutes into testing. We tried to run a 2-hour burn-in on M4 Max host while charging the battery from below 5%, running six bus-powered drives (via ATTO/Black Magic/IOmeter), hitting the RJ45 port for 2.5Gbps (via JPerf), and streaming at least 4K60Hz video content to two display, however, M4 Max will crashed in 20 [minutes.]( https://www.example.com/)

I would like to inquire about Apple's recommended best practices for iPhone thermal management. Specifically, what actions are developers expected to take to prevent the device from overheating? I am aware that we should subscribe to Thermal State Notifications and throttle performance accordingly—such as by reducing streaming quality or temporarily disabling active features. Beyond these measures, are there any other strategies you recommend to mitigate thermal issues and help the device cool down?

I would like to inquire about Apple's recommended best practices for iPhone thermal management. Specifically, what actions are developers expected to take to prevent the device from overheating? I am aware that we should subscribe to Thermal State Notifications and throttle performance accordingly—such as by reducing streaming quality or temporarily disabling active features. Beyond these measures, are there any other strategies you recommend to mitigate thermal issues and help the device cool down?

I want to use FileProvder to implement the function of recovering from the recycle bin (the cloud recycle bin does not move, and after the local recycle bin is restored, the upload event is triggered again), but testing shows that the current recovery from the recycle bin is through the modifyItem event, and the CreateItem event is not triggered again to upload locally restored files Implement the deletion of undelivered files (dateless) without moving them to the recycle bin, which currently appears to be achieved by granting file. dash permission. But it is possible for the content of a file to be manually verified by the user. How can this be solved? How can we dynamically monitor whether a file is dataless Thank you for your reply. Could you please help answer my question

Hello, I have an Asset Pack that's a database. I need to use it in 2 apps. I'm curious at the expected functionality of cross app Asset Pack distribution as I've seen conflicting behavior. (1) Each app is required to have its own unique Background Assets Target. (2) Uploading the asset pack requires the App ID to be included. (3) I'm able to access the Asset Pack of App #1 inside of App #2 by using AssetPackManager.shared.ensureLocalAvailability(of:) with local testing (Not TestFlight) This is a technical question as originally I planned to duplicate the upload of the Asset Pack to both individual apps.

I have a standalone Apple Watch app that uses Bluetooth with the bluetooth-central background mode. It seems that in watchOS 26.2, once the system terminates the BLE connection after background allowance is exceeded, the app never regains background BLE capability, even after the user returns to the foreground and interacts with it. This contradicts the documentation and the WWDC22 “Get timely alerts from Bluetooth devices on watchOS” session, which state that background BLE connectivity should be restored when the user brings the app back to the foreground. Does anyone have any insight into this behavior?

After upgrading to iOS 18, crashes caused by calling null function pointers have changed their crash signal from SIGEGV to SIGKILL, making it impossible for developers to capture crash stacks using third-party components like KSCrash/PLCrashReporter. Is this a design change in iOS 18's memory protection mechanism? If so, are there any officially recommended crash capture solutions? - (void)MockCrashOnNullFunctionPointer { void (*func)(void) = NULL; func(); } Crash report comparison:

I'm having a problem on macOS 26 that has not happened on previous macOS versions. When I call guard url.startAccessingSecurityScopedResource() else { return } try url.bookmarkData(options: [.withSecurityScope]) with url being "file:///", I get an error Error Domain=NSCocoaErrorDomain Code=256 "File descriptor doesn't match the real path." Given that Google returns 0 results on this error, I suppose this is a macOS 26 novelty. (The bookmark data created before upgrading to 26 resolve well). Does anyone already met this or have an idea on how to get around it? The app is a file manager, so having bookmarked access to "/" is crucial.

I am an open source developer, who just switched to macOS a few weeks ago. I am basically looking for an alternative to Linux' /etc/nsswitch.conf. Not for custom DNS resolution, that's an easy problem to solve, but for users / groups / hosts resolution via custom network modules. Basically looking for a way how I can hook up into the OS in kind of the same way as an LDAP client would do, and provide my own NSS modules. Just for reference, I am developing rauthy which can do PAM authn / authz in combination with rauthy-pam-nss. It works perfectly fine on Linux systems, and I now want to make it work on macOS as well. I already know that macOS is running its mDNSResponder for DNS instead of having the nsswitch.conf, but I have not found an answer for users, groups and hosts.

My app allows to save user-selected URLs in a list and browse them with a tap. A user reported that the app often shows that when browsing their saved entry for "On My iPad", it's apparently empty (it contains no files). I saved "On My iPad" in my own list some time ago and noticed that the same issue occurs. The URL seems to be correctly resolved from the saved bookmark data, but I noticed that url.startAccessingSecurityScopedResource() returns false. The other URL I saved some time ago is iCloud Drive, which I can access without issues. If I select "On My iPad" again in a file importer, create new bookmark data from it and resolve the URL from it, access works correctly. I create bookmark data like this: let data = try url.bookmarkData(includingResourceValuesForKeys: [.localizedNameKey, .pathKey, .volumeIsLocalKey]) and resolve URLs like this: let url = try URL(resolvingBookmarkData: data, bookmarkDataIsStale: &bookmarkDataIsStale) bookmarkDataIsStale is false for both the working and not working URLs for "On My iPad". The two bookmark data are different though, even if url.path is the same. What could be the issue?

"We are developing an application use case that requires us to prompt the user to restart their device. We plan to use the system uptime value provided by [NSProcessInfo processInfo].systemUptime to determine if a restart has occurred. Apple's documentation defines this API as 'The amount of time the system has been awake since the last time it was restarted.' Our questions are: Can we reliably use this API, in conjunction with persistent storage, to detect a device restart? Are there any known limitations or considerations when accessing or relying on this API while the application is running in the background?"

When I pass a file path url of a file in iCloud Drive to -[NSWorkspace openURLs:withApplicationAtURL:configuration:completionHandler:], it fails. There is no exception, and the completion handler isn't called. This is in a sandboxed app on macOS 26.1. NSWorkspaceOpenConfiguration* config = NSWorkspaceOpenConfiguration.configuration; config.activates = YES; config.promptsUserIfNeeded = YES; NSLog(@"performDrag 2 with %@", filePathObs); [NSWorkspace.sharedWorkspace openURLs: filePathObs withApplicationAtURL: appURL configuration: config completionHandler: ^(NSRunningApplication * _Nullable app, NSError * _Nullable error) { NSLog(@"performDrag 3"); if (error != nil) { NSLog(@"%@\n%@", error, filePathObs); } NSLog(@"complete performDrag"); }]; NSLog(@"performDrag 4"); In the debug log, the performDrag 2 and performDrag 4 messages appear. I also looked in the Console log, but the only messages that mention my app don't mean anything to me. AFIsDeviceGreymatterEligible Missing entitlements for os_eligibility lookup 6c Reentrant message: kDragIPCCompleted, current message: kDragIPCLeaveApplication