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"

If I'm reading this guide correctly, macOS will automatically/implicitly startAccessingSecurityScopedResource for files opened via drag to Dock icon or NSOpenPanel. And I'm expected to call stopAccessingSecurityScopedResource to balance it once I'm done. Does that mean that if I don't, I'm leaking kernel resources as per the docs? If you fail to relinquish your access to file-system resources when you no longer need them, your app leaks kernel resources. If sufficient kernel resources leak, your app loses its ability to add file-system locations to its sandbox, such as with Powerbox or security-scoped bookmarks, until relaunched. What is this limit in practice for macOS and iOS? I've seen number ranging from 1000-2500. From my testing, iOS does not provide the same implicit startAccessingSecurityScopedResource when using UIDocumentPickerViewController. Is this a correct observation/per design? Now, in the cases where I'm creating an NSURL by resolving a saved bookmark, I'm expected to explicitly startAccessingSecurityScopedResource. Based on this, from what I can tell, this means that I can't universally call startAccessingSecurityScopedResource whenever I access a resource by URL, balanced with a stopAccessingSecurityScopedResource when done, as depending on how I got the URL it might already be implicitly started. Is this a correct observation? Do I need to explicitly check whether I'm on iOS (never implicit?), or macOS (sometimes implicit?), and selectively startAccessingSecurityScopedResource based on every call site that may give me a security-scoped file? If so, is there a complete list of the entrypoints that may give me such files (file dialog, drag and drop, etc)? Thanks!

Hi, I’ve built an app that includes a Contacts Provider Extension (CPE). On iOS 18, I observed the expected behavior — when the main app is uninstalled, the corresponding CPE entry is also removed from the Contacts list. However, on iOS 26, this no longer happens. After uninstalling the app, the CPE remains visible and active in the Contacts list, even though the app is gone.

I got several reports about our TestFlight app crashing unconditionally on 2 devices (iOS 18.1 and iOS 18.3.1) on app start with the following reason: Termination Reason: DYLD 4 Symbol missing Symbol not found: _$sScIsE4next7ElementQzSgyYa7FailureQzYKF (terminated at launch; ignore backtrace) The symbol in question demangles to (extension in Swift):Swift.AsyncIteratorProtocol.next() async throws(A.Failure) -> A.Element? Our deploy target is iOS 18.0, this symbol was introduced in Swift 6.0, we're using latest Xcode 16 now - everything should be working, but for some reason aren't. Since this symbol is quite rarely used directly, I was able to pinpoint the exact place in code related to it. Few days ago I added the following code to our app library (details omitted): public struct AsyncRecoveringStream<Base: AsyncSequence>: AsyncSequence { ... public struct AsyncIterator: AsyncIteratorProtocol { ... public mutating func next(isolation actor: isolated (any Actor)? = #isolation) async throws(Failure) -> Element? { ... } } } I tried to switch to Xcode 26 - it was still crashing on affected phone. Then I changed next(isolation:) to its older version, next(): public mutating func next() async throws(Failure) -> Element? And there crashes are gone. However, this change is a somewhat problematic, since I either have to lower Swift version of our library from 6 to 5 and we loose concurrency checks and typed throws or I'm loosing tests due to Swift compiler crash. Performance is also affected, but it's not that critical for our case. Why is this crash happening? How can I solve this problem or elegantly work around it? Thank you! 2025-10-09_17-13-31.7885_+0100-23e00e377f9d43422558d069818879042d4c5c2e.crash

Hi, I have a macOS app distributed through the App Store that uses an app group to share data with app extensions. The group identifier has the form: .group. In Xcode 26 I am now asked to convert the project to profile based app groups (like on iOS). My question is: Can I convert the project to profile based app groups and will the existing app group (which is prefixed with the Team ID) continue to work (and will exiting users still be able to access their data). If yes, should I add the app group with or without the Team ID prefix to the profile.

I am writing an NSFileProviderReplicatedExtension for my app. Every once in a while it will get to a point where NSFileProviderManager.getDomainsWithCompletionHandler { domains, error in DispatchQueue.main.async { if let error = error { completion(.failure(.domainQueryFailed(error))) } else { completion(.success(domains)) } } } this always fails, once this happens then regardless of what I do - clean build, restart machine, uninstall plugin nothing works. The only way to get back to a wokring state is a full reinstall of the OS. It seems like when this happens Finder gets to a weird irrecoverable state that only a restart can fix. When it fails the error is always : The application cannot be used right now. the only way out is reisntall the OS. When this happened last time, I was advised to the use the debugging profile: https://developer.apple.com/forums/thread/797053 I now have that and have the log which is 300MB file, where do I upload it to? My machine is in that state, is there anything else I can run or diagnose to address this?

I have an odd issue I'm trying to troubleshoot. I have an app that is deployed to our enterprise and works on almost all of our devices. Lately, I have devices (very small number) where the app installs from our MDM and it crashes upon launch, it does not get past the launch screen. If I remove and reinstall the app from the MDM it still crashes. I decided to put the devices in developer mode and if I run the App from Xcode on the device it works fine. If I stop it and run it right from the device it also works. If I do a final build of the app and install it using "Devices and Simulators", the app crashes upon launch. Using "Devices and Simulators" I check for crash log for the app and no file. I am stumped as to whats going on.

After the macOS Sequoia update, my app seems to have an issue with Bluetooth communication between macOS and iOS that uses CoreBluetooth for Central-Peripheral communication. Setup: The iPhone (in my case: iPhone 14 Pro with iOS 18.0 (22A3354)) acts as the Central, and the Mac (in my case: 14" MacBook Pro 2023 with macOS 15.0 (24A335)) as the Peripheral. I’ve implemented a mechanism where the Central (iPhone) sends a message to the Peripheral (Mac) every 15 seconds to keep the connection alive (Because it needs to wait for notify characteristic updates). I never noticed this kind of issue before, but with macOS Sequoia I get it permanently. Issue: The connection drops unexpectedly after a period of time (sometimes 20 seconds, sometimes a few minutes) with CBErrorDomain - code 6: The connection has timed out unexpectedly. Sample Code: Peripheral (Mac): ContentView (Peripheral).txt ContentViewModel (Peripheral).txt Central (iPhone): ContentView (Central).txt ContentViewModel (Central).txt Reproduce: I attached sample code including the Central-Sample (for iPhone) and Peripheral-Sample (for Mac). Just run the Peripheral-Sample (after granting Bluetooth permissions). Then run the Central-Sample and select the Mac device in the list After selecting it should connect, discover the service & characteristic and should start writing messages to it. After some time the func centralManager(_ central: CBCentralManager, didDisconnectPeripheral peripheral: CBPeripheral, error: (any Error)?) {should get called with timed out unexpectedly error. Could anyone please look into this issue and advise on whether there’s a known bug or any workaround? Any guidance would be greatly appreciated, as this impacts the stability of Bluetooth communication between the devices. Thanks in advance. Logs: I also ran the console.app during this issue which got these errors (if this is helpful): console_logs.txt

Hello, I'm working on a project for a file system using FSKit and I'm currently experiencing a strange issue on macOS 26 to which I updated recently. While testing, I'm doing incremental debug builds using Xcode. I'm very careful to make sure I only have a single instance of the built app (hosting the file system extension) anywhere on disk. I run the app, mount the file system, run some tests, unmount, kill the app, make changes, and repeat. Once in a while, however, mount would suddenly start failing with mount: Loading resource: The operation couldn’t be completed. (com.apple.extensionKit.errorDomain error 2.) mount: File system named MyFS not found This would consistently repeat until I clean the build folder, rebuild and run again. I would continue testing for a while, then at some point mount would start failing again. I looked at the system logs and found this message from extensionkitservice: Failed to initialize _EXExtensionIdentity: Error Domain=com.apple.extensionKit.errorDomain Code=5 "Failed to find extension: 24B7F729-5AD1-4486-92B4-1F57CACCA265" So I started going through the logs in more detail and found the following: lsd seems to unregister and register the file system extension occasionally, each time giving it a different UUID. I can see logs about "com.apple.LaunchServices.pluginsregistered" and "com.apple.LaunchServices.pluginsunregistered" notifications being sent with their data. What seems to be the problem is that sometimes after this happens, when I attempt to mount the file system, the extensionkitservice would fail to find the extension because it is referencing it using one of its previous UUIDs assigned by lsd, not its latest one, judging by the UUID in the log message. Am I doing something wrong here? I think I may be causing the constant unregister/register of the extension idirectly by rebuilding via Xcode. Or is it a problem with extensionkitservice? I've never had this happen on Sequoia. macOS 26.0.1 (25A362); Xcode 26.0.1 (17A400) Thank you

I need the USB Host Controller Interface Specification for Apple Silicon to develop low-level USB communication on iOS,could you send me the link to the document?

I am looking to extend the range for a device and the only option from a Bluetooth perspective is Coded PHY but I have not heard of any intent to support it from Apple. Does Apple intend to support Coded PHY and if so what is the roadmap?

I'm developing a Share Extension for a macOS Electron application that allows users to share files from Finder to our application using the system Share menu. The extension compiles, signs, and notarizes successfully, but crashes during initialization due to sandbox restrictions blocking hid-control operations required by NSApplication. The Share Extension crashes during initialization with the following sandbox violation: Process: ShareExtension [pid] Identifier: com.xxxxxxxxxxxx.xxxxxxxxx.extension Operation: hid-control I would appreciate guidance on: The proper entitlements for third-party Share Extensions with App Sandbox Alternative approaches if Share Extensions have fundamental limitations for third-party developers Any documentation or sample code demonstrating Share Extensions outside the App Store

When will Apple mobile phones support some of the optional features of Bluetooth 5... specifically Extended Advertising and LE Coded PHY? There are many applications that benefit from having this capability in the mobile phone.

I have an iOS and macOS app that includes a file provider extension. on macOS is is perfect no issues anywhere. on iOS it works for small datasets or if I do read only operations. as soon as I try to do anything with larger files I quickly hit the 20MB limit. I have solved file transfers by using chunking but when it comes to listing a folder with a couple thousand files it instantly crashes the FPE with an OOM error. works ok up to 100 files but anything beyond that crashes. I know enumerate items supports batches however the initial load form say a webdav server that has no concept of pagination will always fail to load in pieces no matter what I do. This likely explains why WebDAV was never implemented on iOS. in any case can you possibly consider upgrading the memory limit for FPE's or provide some mechanism to call our full iOS app for more processing power in the background to handle requests on demand? I do not understand where 20MB is a reasonable number. even 100MB seems more reasonable with everything have much more memory these days this seems incredibly limiting. even an option to request increased memory with a capability would be fine but that only works for the app itself not the FPE target. please advise if there is anything that can be done.

Hi, I just having an issue with ePassport NFC. When development all requirement setup already included. After build success when trying to scan the passport, it froze there. Nothing happen , look like it not detecting the passport. I check my device and passport no issue. So can help me since its urgent part of the development. It has been blocker since day 1 of the development

I am writing an NSFileProviderExtension for my app. Every once in a while it will get to a point where NSFileProviderManager.getDomainsWithCompletionHandler { domains, error in DispatchQueue.main.async { if let error = error { completion(.failure(.domainQueryFailed(error))) } else { completion(.success(domains)) } } } this always fails, once this happens then regardless of what I do - clean build, restart machine, uninstall plugin nothing works. The only way to get back to a wokring state is a full reinstall of the OS. It seems like when this happens Finder gets to a weird irrecoverable state that only a restart can fix. Is there anything I can do to address this? I have a laptop which is in this state. Finder has this image attached

Hello! I'm working on a mobile app that communicates with a peripheral via Bluetooth with security level 2 in a customised way, as there are also other communication protocols used. We use a bluetooth service with a specific UUID that has a write characteristic for sending data to the device and a notify characteristic for receiving data from the device. After connecting for the first time, a pairing prompt appears after successful connection and subscribing to notifications. When all is set, that is notifications are enabled, a handshake is performed and a communication session is established. There can be only one session for a bluetooth connection. So I have two questions: Regarding the pairing, is there any way that I can know the result of the pairing, so that I could start the handshake after it is accepted? What could be the best approach here? Asking because I noticed some instability on first connection (peripheral ignoring handshake). After disconnecting using Core Bluetooth, the system maintains the connection for some time before actually disconnecting. When opening the app shortly after killing the previous instance, it gets connected very quickly as it reuses the existing connection. The problem is, however, that the device wouldn't accept the new handshake and it is pretty much impossible to reuse previous session. In our use case we need a new BLE connection for each session. Is there any way I could forcibly disconnect from the device or enforce a new connection (not a reused one)? What might be the best approach here? The way I handle it now is by using retrieveConnectedPeripherals and if the device is found to be connected, I use scanning. If the device is advertising then we know it's not connected. Other than that we could also poll retrieveConnectedPeripherals and wait. But obviously it is not optimal, as the user has to wait longer than ususal. Other than that retrievePeripherals is used for getting the peripheral, if the app once found it during scanning. I saw this post describing similar issue, is it the only solution to implement API for disconnecting on the peripheral side?

Application has specified the bluetooth-central background mode. Peripheral Device(BLE) is connected to the iPhone. Application will initiate a request 'retrieveConnectedPeripheralsWithServices' along with list of services to scan for. Application will receive a list of peripherals connected to the system whose service UUID's match. From the list of peripherals, application will initiate a request 'connectPeripheral' with the interested peripheral along with the option set to 'CBConnectPeripheralOptionEnableAutoReconnect'. This option is available from iOS 17+. CBConnectPeripheralOptionEnableAutoReconnect - This option will help in reconnect back to peripheral when peripheral becomes available. (Turn OFF and Turn ON) How do we achieve the same thing in earlier IOS version

I am having a rare crash when calling FileHandle(forWritingTo:) initializer with a file that does not exist. In the documentation, I see that the expected behaviour is to return nil, but in my app, in rare cases I have a Crash. My code that causes the crash is if let handle = try? FileHandle(forWritingTo: logFile) { Is it a known behaviour ? should I test if the file exist before calling FileHandle(forWritingTo:) ? Shareable_2025-09-01_05-32-28.3051.crash

I have a custom object which gets passed back to the main app from XPC. I whitelist it like so: NSSet *expectedClass = [NSSet setWithObjects:[NSArray class], [MyCustomClass class], nil]; [interface setClasses:expectedClass forSelector:@selector(myMethodNameHere:withCompletion:) argumentIndex:0 ofReply:YES]; Now my custom class conforms to NSSecureCoding. It does have an array property of another custom class. @property (nonatomic,readonly) NSArray *arraypropertyOfOtherClass; Which is decoded in -initWithCoder: using: -decodeArrayOfObjectsOfClasses:forKey: Now on macOS Tahoe this is all walking fine. But I just tested on macOS Monterey and I get the following error: Exception: decodeObjectForKey: too many nested collections when explicitly decoding a single collection. How should I handle this for earlier versions of macOS?

We are creating a Replicated FileProvider based application, where we want to handle different types of errors. As per doc: https://developer.apple.com/documentation/fileprovider/synchronizing-files-using-file-provider-extensions?language=objc#Handle-errors-elegantly NSFileProviderErrorNotAuthenticated is a resolvable error, and once we report it, the system throttles the sync operation until something (most likely the app or extension) calls signalErrorResolved(:completionHandler:) to signal that the user or the server resolves the error. But this is not happening in our app, see below the sample code snippet (showing just error related code to keep it concise): NSProgress* MacFileProvider::modifyItem(....) { NSProgress *nsProgress = [[NSProgress alloc] init]; nsProgress.totalUnitCount = NSURLSessionTransferSizeUnknown; NSError *error = [NSError errorWithDomain:NSFileProviderErrorDomain code:NSFileProviderErrorNotAuthenticated userInfo:nil]; completionHandler(nil, 0, false, error); return nsProgress; } Observed behaviour: On making local edits to a file, though this function returns resolvable error, this function is being called multiple times with retry back-off interval. Also, this function is called when we edit other files as well. Expected behaviour: As we are returning resolvable error, system should have throttled the operation until we resolve the error. So, all sync operation should have stopped for any item. Can someone please help understand this behaviour difference, and how to achieve the expected behaviour.