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"

Does Bluetooth work in the background in iOS 26?

I’m facing an issue in our native iOS app that occurs specifically on iOS 26.1 (not observed on any lower versions). When I update a @State field value, the UI does not reflect the change as expected. The @State variable updates internally, but the view does not re-render. This behaviour started after upgrading to iOS 26.1. Works fine on iOS 26.0 and earlier versions. Has anyone else encountered this issue or found a workaround? Any insights or suggestions would be greatly appreciated.

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?

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'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.

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 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?

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

With the RC version of macOS 26, an issue persists when you try to create a bookmark with security scope for the root folder "/". This leads to an error "The file couldn’t be opened.". However, you can create bookmark for /Applications, /System, /Users... This is quite annoying for one of my app because a user can create a cartography of his disk usage, and the access to the root folder "/" is the only way to do so! Is there a workaround? PS: reported the issue with ID FB20186406 let openPanel = NSOpenPanel() openPanel.canChooseDirectories = true openPanel.canChooseFiles = false openPanel.beginSheetModal(for: self.view.window!) { (result) in guard result == .OK, let folderURL = openPanel.url else { return } openPanel.close() do { let data = try folderURL.bookmarkData(options: .withSecurityScope, includingResourceValuesForKeys: nil, relativeTo: nil) print("Bookmark data was created for \(folderURL.path)") } catch (let error) { print("Error creating bookmark for \(folderURL.path), with error: \(error.localizedDescription)") } }

I face this issue only on macOS 26 and only on the Intel architecture. I'm unable to download files from a file provider's folder when I make them read-only. STEPS TO REPRODUCE Download the sample from https://developer.apple.com/documentation/fileprovider/synchronizing-files-using-file-provider-extensions?language=objc Follow the steps on the page to configure the project. Build the project. Run it. Add a domain. Open the domain's folder in the Finder. Move a file to the domain's folder. Right-click on the file in the domain's folder and select "Remove Download". Close the Finder's window with the domain's folder and kill all the "Provider" processes to get rid of running instances of the extension. Change Item's capabilities in Item.swift to make the items read-only: var result: NSFileProviderItemCapabilities = [ .allowsContentEnumerating, .allowsReading ] Rebuild the project and run it. Open the domain's folder and try to drag and drop the file from the extension's folder to, let's say, the Desktop folder. EXPECTED RESULT The file is copied ACTUAL RESULT A dialog pops up with text "The file “filename” cannot be downloaded. Do you want to skip it?" Stop/Skip

I am able to symbolicate kernel backtraces for addresses that belong to my kext. Is it possible to symbolicate kernel backtraces for addresses that lie beyond my kext and reference kernel code? Sample kernel panic log