XPC is a a low-level (libSystem) interprocess communication mechanism that is based on serialized property lists.

Posts under XPC tag

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System Network Extension XPC with LaunchAgent
I've discovered that a system network extension can communicate with a LaunchDaemon (loaded using SMAppService) over XPC, provided that the XPC service name begins with the team ID. If I move the launchd daemon plist to Contents/Library/LaunchAgents and swap the SMAppService.daemon calls to SMAppService.agent calls, and remove the .privileged option to NSXPCConnection, the system extension receives "Couldn't communicate with a helper application" as an error when trying to reach the LaunchAgent advertised service. Is this limitation by design? I imagine it is, but wanted to check before I spent any more time on it.
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192
Jul ’25
Recommended / Canonical way to host remote (separate process) SwiftUI views.
I am building a tool that enables the user to write, auto-compile and interact with SwiftUI code (think something like a mini Xcode Canvas). Which so far works really well. The app is not sandboxed since it uses tools like swiftc and sourcekit-lsp. The obvious problem here is that since the 'Preview' part of the app is driven by arbitrary code a crash/hang there would lead to a termination of the whole app. I understand that there are some private apis like NSRemoteView or CALayerHost but I would like to avoid them if I can. From what I see reading other similar solutions IOSurface sharing + event forwarding might be the best solution. So my question is: Is there a proper or recommended way to achieve this? Meaning having a fully interactive SwiftUI view presented in my host app but running on a separate process? Any pointers to the right direction or examples or whatever could help me with this would be greatly appreciated.
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Jul ’25
can an xpc service access the keychain.
I am trying to create an app bundle with an xpc service. The main app creates a keychain item, and attempts to share (keychain access groups) with the xpc service it includes in its bundle. However, the xpc service always encounters a 'user interaction not allowed' error regardless of how I create the keychain item. kSecAttrAccessiblei is set to kSecAttrAccessibleWhenUnlockedThisDeviceOnly, the keychain access group is set for both the main app and the xpc service and in the provisioning profile. I've tried signing and notarizing. Is it ever possible for an xpc service to access the keychain? This all on macos 15.5.
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Jul ’25
ExtensionKit & ExtensionFoundation process lifecycle
An XPC service’s process has a system-managed lifecycle: the process is launched on-demand when another process tries to connect to it, and the system can decide to kill it when system resources are low. XPC services can tell the system when they shouldn’t be killed using xpc_transaction_begin/end. Do extensions created with ExtensionFoundation and/or ExtensionKit have the same behavior?
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155
Jul ’25
XPC between endpoint security and host application
Hello, I am having some issues with running an XPC server on an endpoint security and connecting to it from the sandboxed host application. I tried doing the following: setting xpc server in endpoint security extension entitlements: <key>com.apple.developer.endpoint-security.client</key> <true/> <key>com.apple.security.xpc.server</key> <true/> Adding the mach service with the plist: <dict> <key>NSExtension</key> <dict> <key>NSExtensionPointIdentifier</key> <string>com.apple.system-extension-endpoint-security</string> <key>NSExtensionPrincipalClass</key> <string>$(PRODUCT_MODULE_NAME).ESFExtension</string> </dict> <key>NSEndpointSecurityMachServiceName</key> <string>[TEAMID]com.[UNIQUE_ID]</string> </dict> </plist> Putting a mach-lookup in sandboxed host application entitlements <dict> <key>com.apple.security.app-sandbox</key> <true/> <key>com.apple.security.files.user-selected.read-only</key> <true/> <key>com.apple.developer.system-extension.install</key> <true/> <key>com.apple.security.exception.mach-lookup.global-name</key> <array> <string>[TEAMID]com.[UNIQUE_ID]</string> </array> </dict> Creating the server in the system extension using xpc_connection_create_mach_service(_service_name.c_str(), dispatch_get_main_queue(), XPC_CONNECTION_MACH_SERVICE_LISTENER); with _service_name being the same as in the mach-lookup entitlement. And connecting to it in the host app with: xpc_connection_create_mach_service([self.serviceName UTF8String], dispatch_get_main_queue(), 0); My problem is I get an xpc error 159 (sandbox restriction) in the lookup (libxpc.dylib) [com.apple.xpc:connection] [0x600001a7db30] failed to do a bootstrap look-up: xpc_error=[159: Unknown error: 159] I tried putting the sysex and the host app in the same app group, and it didn't help and I also read this is bad practice to have an app group between a sandboxed app and a system extension so I removed it. I tried adding a temporary-exception and with it, the code works properly. I tried with the XPC_CONNECTION_MACH_SERVICE_PRIVILEGED flag but it still didn't work. Is it possible to have an XPC connection between a ES sysex and it's host app? Should the service name have a prefix of the bundle name or does it must have a certain pattern? Do I need to add some capability in the Certificates, Identifiers & Profiles? Thanks for helping.
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Jun ’25
XPC connection consistently invalidated on app upgrade
Hi, Our project is a MacOS SwiftUI GUI application that bundles a System Network Extension, signed with a Developer ID certificate for distribution outside of the app store. The system network extension is used to write a packet tunnel provider. The signing of the app & network extension is handled by XCode (v16.0.0), we do not run codesign ourselves. We have no issues with XPC or the system network extension during normal usage, nor when the application is installed on a user's device for the first time. The problem only arises when the user upgrades the application. I have experienced this issue myself, as have our users. It's been reported on Apple Silicon macbooks running at least macOS 15.3.2. Much like the SimpleFirewall example (which we used as a reference), we use XPC for basic communication of state between the app and NE. These XPC connections stop working when the user installs a new version of the app, with OS logs from the process indicating that the connection is immediately invalidated. Subsequent connection attempts are also immediately invalidated. Toggling the VPN in system settings (or via the app) does not resolve the problem, nor does restarting the app, nor does deleting and reinstalling the app, nor does restarting the device. The only reliable workaround is to delete the system extension in Login Items & Extensions, under Network Extensions. No device restart is necessary to garbage collect the old extension - once the extension is reapproved by the user, the XPC issue resolves itself. This would be an acceptable workaround were it possible to automate the deleting of the system extension, but that appears deliberately not possible, and requiring our users to do this each time they update is unreasonable. When the upgraded app is opened for the first time, the OSSystemExtensionRequest request is sent, and the outcome is that the previously installed system network extension is replaced, as both the CFBundleVersion and CFBundleShortVersionString differ. When this issue is encountered, the output of systemextensionsctl list shows the later version is installed and activated. I've been able to reproduce this bug on my personal laptop, with SIP on and systemextensionsctl developer off, but on my work laptop with SIP off and systemextensionsctl developer on (where the network extension is replaced on each activation request, instead of only when the version strings differ), I do not encounter this issue, which leads me to believe it has something to do with the notarization process. We notarize the pkg using xcrun notarytool, and then staple to the pkg. This is actually the same issue described in: https://developer.apple.com/forums/thread/711713 https://developer.apple.com/forums/thread/667597 https://developer.apple.com/forums/thread/742992 https://developer.apple.com/forums/thread/728063 but it's been a while since any of these threads were updated, and we've made attempts to address it off the suggestions in the threads to no avail. Those suggestions are: Switching to a .pkg installer from a .dmg As part of the .pkg preinstall, doing all of the following: Stopping the VPN (scutil --nc stop), shutting down the app (using osascript 'quit app id'), and deleting the app (which claims to delete the network extension, but not the approval in Login Items & Extensions remains??), by running rm -rf on the bundle in /Applications As part of the .pkg postinstall: Forcing macOS to ingest the App bundle's notarization ticket using spctl --assess. Ensuring NSXPCListener.resume() is called after autoreleasepool { NEProvider.startSystemExtensionMode() } (mentioned in a forum thread above as a fix, did not help.) One thing I'm particularly interested in is the outcome of this feedback assistant ticket, as I can't view it: FB11086599. It was shared on this forum in the first thread above, and supposedly describes the same issue. I almost find it hard to believe that this issue has been around for this many years without a workaround (there's system network extension apps out there that appear to work fine when updating, are they not using XPC?), so I wonder if there's a fix described in that FB ticket. Since I can't view that above feedback ticket, I've created my own: FB17032197
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Jun ’25
ExtensionKit and iOS 26
It looks like ExtensionKit (and ExtensionFoundation) is fully available on iOS 26 but there is no mention about this in WWDC. From my testing, it seems as of beta 1, ExtensionKit allows the app from one dev team to launch extension provided by another dev team. Before we start building on this, can someone from Apple help confirm this is the intentional behavior and not just beta 1 thing?
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Jun ’25
Cross process URL bookmark
I am developing a background application that acts as a metadata server under MacOS written in Swift. Sandboxed clients prompt the user to select URLs which are passed to the server as security scoped bookmarks via an App Group and the metadata will be passed back. I don't want the I/O overhead of passing the complete image file data to the server. All the variations I have tried of creating security scoped bookmarks in the client and reading them from the server fail with error messages such as "The file couldn’t be opened because it isn’t in the correct format." Can anyone guide me in the right direction or is this just not possible?
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Jun ’25
XPC activity doesn’t fire while main app is closed
Hi, I have a sandboxed app with a bundled sandboxed XPC service. When it’s launched, the XPC service registers a repeating XPC activity with the system. The activity’s handler block does get called regularly like I’d expect, but it stops being called once the main app terminates. What’s the recommended way to fix this issue? Could I have a bundled XPC service double as a launch agent, or would that cause other problems?
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May ’25
XPC Connection Error
I have an accessory with MFi authenticaiton passed(got 0xAA05) and identification accepted (got 0x1D02). But when I try to open the target stream by using iAP2 EA session framework, I always enounter the same error looking like: XPC connection error: Error Domain=NSCocoaErrorDomain Code=4099 "The connection to service named com.apple.accessories.externalaccessory-server was invalidated from this process." UserInfo={NSDebugDescription=The connection to service named com.apple.accessories.externalaccessory-server was invalidated from this process.} anybody can tell me what it related with? And what can I do to go through it quickly? Thank you much in advance.
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103
May ’25
SMAppService getting notified when status changes externally (from System Settings)
Say I want to sync a toggle in my app with SMAppService's .status property. If the status changes from my app I can track it. But if user toggles it from System Settings, I don't see a notification so then the UI in my app is out of date. The status property is not key value observable and there doesn't appear to be a SMAppServiceStatusDidChangeNotification ? I can re-read it every time my app will become active but feels kind of wrong to do it this way.
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May ’25
Action Extension Won't Launch Outside Mac App Store: Prompting policy for hardened runtime; service: kTCCServiceAppleEvents requires entitlement com.apple.security.automation.apple-events but it is missing
I have an outside Mac App Store app. It has an action extension. I can't get it to run from Xcode. I try to debug it from Safari. It shows up in the menu when I click the 'rollover' button but it doesn't show up in the UI at all. Xcode doesn't give me any indication as to what the problem is. I see this logs out in console when I try to open the action extension: Prompting policy for hardened runtime; service: kTCCServiceAppleEvents requires entitlement com.apple.security.automation.apple-events but it is missing for accessing={TCCDProcess: identifier=BundleIdForActionExtHere, pid=6650, auid=501, euid=501, binary_path=/Applications/AppNamehere.app/Contents/PlugIns/ActionExtension.appex/Contents/MacOS/ActionExtension}, requesting={TCCDProcess: identifier=com.apple.appleeventsd, pid=550, auid=55, euid=55, binary_path=/System/Library/CoreServices/appleeventsd}, I don't see why the Action extension needs Apple events but I added it to the entitlements anyway but it doesn't seem to matter. The action extension fails to open.
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May ’25
communication between live activity and main app
I found the live activity process cannot write to the app group and FileManger, can only read the app group. When I write using FileManager in a live activity process, the console prompts me with a permission error. When I write using UserDefault(suit:) in the live activity process, I read a null value in the main app. Is this the case for real-time event design? I haven’t seen any documentation mentioning this. Does anyone know, thank you very much.
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May ’25
NSXPCListener only working while Debugging `listener failed to activate: xpc_error=[1: Operation not permitted]`
I am building a Mac app that launch a GUI helper app and use XPC to communicate between them. Main app start a XPC Listener using NSXPCListener(machServiceName: "group.com.mycompany.myapp.xpc") Launch the helper app Helper app connect to the XPC service and listen command from main app. What I observe is the app seems can start XPC listener while I run it via Xcode. If I run the app using TestFlight build, or via the compiled debug binary (same one that I use on Xcode), it cannot start the XPC service. Here is what I see in the Console: [0x600000ef7570] activating connection: mach=true listener=true peer=false name=group.com.mycompany.myapp.xpc [0x600000ef7570] listener failed to activate: xpc_error=[1: Operation not permitted] Both main app and helper app are sandboxed and in the same App Group - if they were not, I cannot connect the helper app to main app. I can confirm the entitlement profiles did contain the app group. If I start the main app via xcode, and then launch the helper app manually via Finder, the helper app can connect to the XPC and everything work. It is not related to Release configuration, as the same binary work while I am debugging, but not when I open the binary manually. For context, the main app is a Catalyst app, and helper app is an AppKit app. To start a XPC listener on Catalyst, I had do it in a AppKit bridge via bundle. Given the app worked on Xcode, I believe this approach can work. I just cannot figure out why it only work while I am debugging. Any pointer to debug this issue is greatly appreciated. Thanks!
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May ’25
Cleanup LaunchAgents after development
I have been playing with application bundled LaunchAgents: I downloaded Apple sample code, Run the sample code as is, Tweaked the sample code a lot and changed the LaunchAgents IDs and Mach ports IDs, Created new projects with the learnings, etc. After deleting all the Xcode projects and related project products and rebooting my machine several times, I noticed the LaunchAgent are still hanging around in launchctl. If I write launchctl print-disabled gui/$UID (or user/$UID) I can see all my testing service-ids: disabled services = { "com.xpc.example.agent" => disabled "io.dehesa.apple.app.agent" => disabled "io.dehesa.sample.app.agent" => disabled "io.dehesa.example.agent" => disabled "io.dehesa.swift.xpc.updater" => disabled "io.dehesa.swift.agent" => disabled } (there are more service-ids in that list, but I removed them for brevity purposes). I can enable or disable them with launchctl enable/disable service-target, but I cannot really do anything else because their app bundle and therefore PLIST definition are not there anymore. How can I completely remove them from my system? More worryingly, I noticed that if I try to create new projects with bundled LaunchAgents and try to reuse one of those service-ids, then the LaunchAgent will refuse to run (when it was running ok previously). The calls to SMAppService APIs such .agent(plistName:) and register() would work, though.
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May ’25
Is there an API to programmatically obtain an XPC Service's execution context?
Hello! I'm writing a System Extension that is an Endpoint Security client. And I want to Deny/Allow executing some XPC Service processes (using the ES_EVENT_TYPE_AUTH_EXEC event) depending on characteristics of a process that starts the XPC Service. For this purpose, I need an API that could allow me to obtain an execution context of the XPC Service process. I can obtain this information using the "sudo launchctl procinfo <pid>" command (e.g. I can use the "domain = pid/3428" part of the output for this purpose). Also, I know that when the xpcproxy process is started, it gets as the arguments a service name and a pid of the process that requests the service so I can grasp the execution context from xpcproxy launching. But are these ways to obtain this info legitimate?
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Apr ’25
iOS not launching my app network extension, it seemingly isn't crashing it either
My personal project is a bit further along however after not being able to get this to work in my app I fell back to a much simpler/proven implementation out there. There is this project on GitHub with a guide that implements a barebones app extension with packet tunneling. I figure this can give us common ground. After changing the bundle and group identifiers to all end with -Caleb and or match up I tried running the app. The app extension does not work whatsoever and seemingly for reasons that are similar to my personal project. If I pull up the console and filter for the subsystem (com.github.kean.vpn-client-caleb.vpn-tunnel) I see the following. First you see installd installing it 0x16ba5f000 -[MIUninstaller _uninstallBundleWithIdentity:linkedToChildren:waitForDeletion:uninstallReason:temporaryReference:deleteDataContainers:wasLastReference:error:]: Destroying container com.github.kean.vpn-client-caleb.vpn-tunnel with persona 54D15361-A614-4E0D-931A-0953CDB50CE8 at /private/var/mobile/Containers/Data/PluginKitPlugin/2D0AE485-BB56-4E3E-B59E-48424CD4FD65 And then installd says this (No idea what it means) 0x16b9d3000 -[MIInstallationJournalEntry _refreshUUIDForContainer:withError:]: Data container for com.github.kean.vpn-client-caleb.vpn-tunnel is now at /private/var/mobile/Containers/Data/PluginKitPlugin/2D0AE485-BB56-4E3E-B59E-48424CD4FD65 Concerningly runningboardd seems to immediately try and stop it? Executing termination request for: <RBSProcessPredicate <RBSProcessBundleIdentifiersPredicate| {( "com.github.kean.vpn-client-caleb", "com.github.kean.vpn-client-caleb.vpn-tunnel" )}>> [app<com.github.kean.vpn-client-caleb(54D15361-A614-4E0D-931A-0953CDB50CE8)>:1054] Terminating with context: <RBSTerminateContext| explanation:installcoordinationd app:[com.github.kean.vpn-client-caleb/54D15361-A614-4E0D-931A-0953CDB50CE8] uuid:963149FA-F712-460B-9B5C-5CE1C309B2FC isPlaceholder:Y reportType:None maxTerminationResistance:Absolute attrs:[ <RBSPreventLaunchLimitation| <RBSProcessPredicate <RBSProcessBundleIdentifiersPredicate| {( "com.github.kean.vpn-client-caleb", "com.github.kean.vpn-client-caleb.vpn-tunnel" )}>> allow:(null)> ]> Then runningboardd leaves a cryptic message Acquiring assertion targeting system from originator [osservice<com.apple.installcoordinationd>:244] with description <RBSAssertionDescriptor| "installcoordinationd app:[com.github.kean.vpn-client-caleb/54D15361-A614-4E0D-931A-0953CDB50CE8] uuid:963149FA-F712-460B-9B5C-5CE1C309B2FC isPlaceholder:Y" ID:33-244-5222 target:system attributes:[ <RBSPreventLaunchLimitation| <RBSProcessPredicate <RBSProcessBundleIdentifiersPredicate| {( "com.github.kean.vpn-client-caleb", "com.github.kean.vpn-client-caleb.vpn-tunnel" )}>> allow:(null)> ]> And that seems to be all I have to go off of.... If I widen my search a bit I can see backboardd saying things like Connection removed: IOHIDEventSystemConnection uuid:57E97E5D-8CDE-467B-81CA-36A93C7684AD pid:1054 process:vpn-client type:Passive entitlements:0x0 caller:BackBoardServices: <redacted> + 280 attributes:{ HighFrequency = 1; bundleID = "com.github.kean.vpn-client-caleb"; pid = 1054; } state:0x1 events:119 mask:0x800 dropped:0 dropStatus:0 droppedMask:0x0 lastDroppedTime:NONE Or Removing client connection <BKHIDClientConnection: 0xbf9828cd0; IOHIDEventSystemConnectionRef: 0xbf96d9600; vpid: 1054(vAF7); taskPort: 0x5D777; bundleID: com.github.kean.vpn-client-caleb> for client: IOHIDEventSystemConnection uuid:57E97E5D-8CDE-467B-81CA-36A93C7684AD pid:1054 process:vpn-client type:Passive entitlements:0x0 caller:BackBoardServices: <redacted> + 280 attributes:{ HighFrequency = 1; bundleID = "com.github.kean.vpn-client-caleb"; pid = 1054; } state:0x1 events:119 mask:0x800 dropped:0 dropStatus:0 droppedMask:0x0 lastDroppedTime:NONE source:HID There's really nothing in the sysdiagnose either. No crash no nothing. I am stumped. Any idea what might be going wrong for me here? Has something about the way app extensions or sandbox rules work changed in later OSes?
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Apr ’25
setCodeSigningRequirement seems not to work in new Service Management API setup.
I have developed a sample app following the example found Updating your app package installer to use the new Service Management API and referring this discussion on XPC Security. The app is working fine, I have used Swift NSXPCConnection in favour of xpc_connection_create_mach_service used in the example. (I am running app directly from Xcode) I am trying to set up security requirements for the client connection using setCodeSigningRequirement on the connection instance. But it fails for even basic requirement connection.setCodeSigningRequirement("anchor apple"). Error is as follows. cannot open file at line 46986 of [554764a6e7] os_unix.c:46986: (0) open(/private/var/db/DetachedSignatures) - Undefined error: 0 xpc_support_check_token: anchor apple error: Error Domain=NSOSStatusErrorDomain Code=-67050 "(null)" status: -67050 I have used codesign -d --verbose=4 /path/to/executable to check the attributes I do get them in the terminal. Other way round, I have tried XPC service provider sending back process id (pid) with each request, and I am probing this id to get attributes using this code which gives all the details. func inspectCodeSignature(ofPIDString pidString: String) { guard let pid = pid_t(pidString) else { print("Invalid PID string: \(pidString)") return } let attributes = [kSecGuestAttributePid: pid] as CFDictionary var codeRef: SecCode? let status = SecCodeCopyGuestWithAttributes(nil, attributes, [], &codeRef) guard status == errSecSuccess, let code = codeRef else { print("Failed to get SecCode for PID \(pid) (status: \(status))") return } var staticCode: SecStaticCode? let staticStatus = SecCodeCopyStaticCode(code, [], &staticCode) guard staticStatus == errSecSuccess, let staticCodeRef = staticCode else { print("Failed to get SecStaticCode (status: \(staticStatus))") return } var infoDict: CFDictionary? if SecCodeCopySigningInformation(staticCodeRef, SecCSFlags(rawValue: kSecCSSigningInformation), &infoDict) == errSecSuccess, let info = infoDict as? [String: Any] { print("🔍 Code Signing Info for PID \(pid):") print("• Identifier: \(info["identifier"] ?? "N/A")") print("• Team ID: \(info["teamid"] ?? "N/A")") if let entitlements = info["entitlements-dict"] as? [String: Any] { print("• Entitlements:") for (key, value) in entitlements { print(" - \(key): \(value)") } } } else { print("Failed to retrieve signing information.") } var requirement: SecRequirement? if SecRequirementCreateWithString("anchor apple" as CFString, [], &requirement) == errSecSuccess, let req = requirement { let result = SecStaticCodeCheckValidity(staticCodeRef, [], req) if result == errSecSuccess { print("Signature is trusted (anchor apple)") } else { print("Signature is NOT trusted by Apple (failed anchor check)") } } var infoDict1: CFDictionary? let signingStatus = SecCodeCopySigningInformation(staticCodeRef, SecCSFlags(rawValue: kSecCSSigningInformation), &infoDict1) guard signingStatus == errSecSuccess, let info = infoDict1 as? [String: Any] else { print("Failed to retrieve signing information.") return } print("🔍 Signing Info for PID \(pid):") for (key, value) in info.sorted(by: { $0.key < $1.key }) { print("• \(key): \(value)") } } If connection.setCodeSigningRequirement does not works I plan to use above logic as backup. Q: Please advise is there some setting required to be enabled or I have to sign code with some flags enabled. Note: My app is not running in a Sandbox or Hardened Runtime, which I want.
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239
Apr ’25
Launch daemon running but XPC is down
Hello, I have a question about a edge case scenario. Before that some info on my project- I have a launchdaemon that carries out some business logic, it also has XPC listener (built using C APIs). Question- Can there be a situation when the daemon is up and running but the XPC listener is down(due to some error or crash)? If yes then do I need to handle it in my code or launchd will handle it? when the daemon is stopped or shut down, how do I stop the XPC listener? After getting listener object from xpc_connection_create_mach_service should I just call xpc_connection_cancel followed by a call to xpc_release? Thanks! K
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Apr ’25