Hello,
I run into an issue on Monterey (12.7.5). I have a bundled XPC service in my application which is displaying some stuff and playin sounds via NSSound.
I had a problem with playback due to service priority, so I use the trick with a reply block where I send a reply block to the service and basically just retain it and never call it.
This worked fine so far, but we have users, predominantly on Monterey, who are having a problem with sound playback. It's choppy and distorted when their machine is under load (where "load" often just means playing a video on YouTube in Chrome).
Is there anything else I can do to get the proper priority for my xpc service so I can avoid distorted sound?
Additionally the service type is Application and RunLoopType is NSRunLoop with JoinExistingSession set to true. The QoS level of main queue is 0x21 (user interactive) and I'm calling all the NSSound APIs on main queue.
Processes & Concurrency
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I’m currently developing an app that communicates with a BLE dongle. When I swipe up to close the app on my phone, both the phone app and the CarPlay app are terminated. From the CarPlay interface, I can relaunch the app. My question is: Can CarPlay establish a connection with a BLE dongle when the phone app is fully closed or not running in the background?
Topic:
App & System Services
SubTopic:
Processes & Concurrency
Tags:
IOBluetooth
CarPlay
Core Bluetooth
Context/Project Idea:
I'm currently developing a project that consists of a macOS application using Swift and a local Python backend that executes specific tasks such as processing data. The Python backend is the core of this project, while the Swift application is a mere interface to interact with it.
These two project parts should be decoupled so the user can theoretically run their own backend and connect the Swift application to it. Likewise, the user should be able to connect to the shipped backend using, e.g. curl.
Current plan:
My main idea is to use launchctl to launch a launchd agent which runs the Python backend. The script launching the backend will generate an API key stored in a keychain access group. The Swift application can then get that key and access the backend. The user can always get that API key from the keychain if they want to connect to it programmatically.
Here are the main questions I have currently:
Python Interpreter Consistency: I'm exploring options such as cx_Freeze or PyInstaller to create a standalone Python executable for better system stability. Does anyone have experience with these tools in a macOS environment, or are there other reliable alternatives worth considering?
Adding a Launchd Agent to Xcode: How can I add a launchd agent to my Xcode project to manage a Python executable built with cx_Freeze or PyInstaller? What steps should I follow to ensure it functions properly?
Keychain Access for Launchd Agent: Is it feasible for a launchd agent to access a Keychain access group? What configurations or permissions are necessary to implement this?
Thanks in advance!
Topic:
App & System Services
SubTopic:
Processes & Concurrency
Tags:
macOS
Entitlements
Service Management
Code Signing
Per Quinn the Eskimo's great summary post I am looking for the WWDC 2020 Session 10063 "Background execution demystified" but all links seem to be broken or redirecting elsewhere. Does anyone know where one could find a reputable copy of the video to watch as we explore background execution?
On iPhone, we can use iBeacon to wake up the APP in the background for Bluetooth scanning connection, now we want to port the function to AppleWatch APP, but the API related to iBeacon is not applicable on watchOS, does watchOS have a similar wake up mechanism?
Topic:
App & System Services
SubTopic:
Processes & Concurrency
Tags:
WatchKit
watchOS
Maps and Location
Core Bluetooth
I updated my computer to Sonoma, and now my LaunchDaemon will not load.
I have the following setup :
File in /Library/LaunchDaemons/com.startup.plist
like this :
<?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.startup</string>
<key>ProgramArguments</key>
<array>
<string>/usr/local/bin/bash</string>
<string>/Library/Scripts/Startup/startup.sh</string>
</array>
<key>RunAtLoad</key>
<true/>
<key>StandardErrorPath</key>
<string>/tmp/com.startup.stderr</string>
<key>StandardOutPath</key>
<string>/tmp/com.startup.stdout</string>
</dict>
</plist>
File in File in /Library/Scripts/Startup/startup.sh
#!/bin/zsh
PATH=/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Users:/Users/root:/Users/root/Scripts:/Library/Scripts:/Library/Scripts/Startup
#Load modules for Fuse
/Library/Filesystems/macfuse.fs/Contents/Resources/load_macfuse
/usr/sbin/sysctl -w vfs.generic.macfuse.tunables.allow_other=1
#Connect to XXXXXX_net
/bin/sleep 28
myip=0
while [ $myip = 0 ]
do
/bin/sleep 3
myip=$(ifconfig -l | xargs -n1 ipconfig getifaddr)
done
/usr/local/bin/sshfs XXXX@XXXXXX.net: /Volumes/XXXXXX.net -o local,auto_cache,reconnect,ServerAliveInterval=15,ServerAliveCountMax=3,ConnectTimeout=5,daemon_timeout=60,iosize=2097152,volname=XXXXXX.net,allow_other,defer_permissions,async_read,Ciphers=aes128-gcm@openssh.com,Cipher=aes128-gcm@openssh.com,compression=no
And then we need some commands to be run as root user during boot :
/private/etc/sudoers.d/startup-script-nopasswd
username ALL = (root) NOPASSWD: /usr/sbin/sysctl
username ALL = (root) NOPASSWD: /usr/local/bin/sshfs
As of now, I cant even get the /Library/LaunchDaemons/com.startup.plist
to run after i updated the macOS to Sonoma ….
Topic:
App & System Services
SubTopic:
Processes & Concurrency
Tags:
macOS
Zsh
Scripting
Command Line Tools
I have a process [command line cpp application] which i want to run always such as it should relaunch after a crash, after device startup etc.
I created a launchd Property List File with KeepAlive true and placed under /Library/LaunchDaemons.
Problem Statements:
I have a bash script to start and stop this process.
start using: launchctl bootstrap.
stop involve these two steps:
send SIGTERM signal and wait untill process stops after doing some cleanups
launchctl bootout [It doesn't sends SIGTERM]
during steps 1 - Process is getting stop, but also getting immediate relaunch by launchctl
during step 2 - it getting stop again.
is there a proper way so that we can disable KeepAlive temporarily so that process will not launch during step 1?
or suggest other ways to handle this?
I am trying to migrate a WatchConnectivity App to Swift6 and I found an Issue with my replyHandler callback for sendMessageData.
I am wrapping sendMessageData in withCheckedThrowingContinuation, so that I can await the response of the reply. I then update a Main Actor ObservableObject that keeps track of the count of connections that have not replied yet, before returning the data using continuation.resume.
...
@preconcurrency import WatchConnectivity
actor ConnectivityManager: NSObject, WCSessionDelegate {
private var session: WCSession = .default
private let connectivityMetaInfoManager: ConnectivityMetaInfoManager
...
private func sendMessageData(_ data: Data) async throws -> Data? {
Logger.shared.debug("called on Thread \(Thread.current)")
await connectivityMetaInfoManager.increaseOpenSendConnectionsCount()
return try await withCheckedThrowingContinuation({
continuation in
self.session.sendMessageData(
data,
replyHandler: { data in
Task {
await self.connectivityMetaInfoManager
.decreaseOpenSendConnectionsCount()
}
continuation.resume(returning: data)
},
errorHandler: { (error) in
Task {
await self.connectivityMetaInfoManager
.decreaseOpenSendConnectionsCount()
}
continuation.resume(throwing: error)
}
)
})
}
Calling sendMessageData somehow causing the app to crash and display the debug message: Incorrect actor executor assumption.
The code runs on swift 5 with SWIFT_STRICT_CONCURRENCY = complete.
However when I switch to swift 6 the code crashes.
I rebuilt a simple version of the App. Adding bit by bit until I was able to cause the crash.
See Broken App
Awaiting sendMessageData and wrapping it in a task and adding the @Sendable attribute to continuation, solve the crash.
See Fixed App
But I do not understand why yet.
Is this intended behaviour?
Should the compiler warn you about this?
Is it a WatchConnectivity issue?
I initially posted on forums.swift.org, but was told to repost here.
Topic:
App & System Services
SubTopic:
Processes & Concurrency
Tags:
Watch Connectivity
Swift
Concurrency
Hello,
My team has developed a DNS proxy for macOS. We have this set up with a system extension that interacts with the OS, and an always-running daemon that does all the heavy lifting. Communication between the two is DNS request and response packet traffic.
With this architecture what are best practices for how the system extension communicates with a daemon?
We tried making the daemon a socket server, but the system extension could not connect to it.
We tried using XPC but it did not work and we could not understand the errors that were returned.
So what is the best way to do this sort of thing?
Topic:
App & System Services
SubTopic:
Processes & Concurrency
Tags:
XPC
System Extensions
Network Extension
Service Management
I have several processes maintaining NSXPConnection to an XPC service. The connections are bi-directional. Each side service and clients) of the connection exports an object, and an XPCInterface. The @protocols are different - to the service, and from the service to clients.
So long as all the "clients" fully implement their "call-back" @protocol, there's no problem. All works fine.
However - If a client does NOT implement a method in the "call back protocol", or completely neglects to export an object, or interface - and the service attempts to call back using the nonexistent method -- the XPC connection invalidates immediately.
So far - expected behaviour.
However, if I want the service to behave to the client a little like a "delegate" style -- and check first whether the client "respondsToSelector" or even - supports an interface BEFORE calling it, then this doesn't work.
When my XPC service tries the following on a client connection:
if (xpcConnection.remoteObjectInterface == nil)
os_log_error(myXPCLog, "client has no remote interface);
the condition is never met - i.e. the "remoteObjectInterface is never nil even when the client does NOT configure its NSXPCConnection with any incoming NSXPCInterface, and does not set an "exportedObject"
Furthermore, the next check:
if ([proxy respondsToSelector:@selector(downloadFiltersForCustomer:withReply:)]) {
}
will not only fail - but will drop the connection. The client side gets the invalidation with the following error:
<NSXPCConnection: 0x600000b20000> connection to service with pid 2477 named com.proofpoint.ecd: received an undecodable message for proxy 1 (no exported object to receive message). Dropping message.
I guess the "undecidable message" is the respondsToSelector - because the code doesn't get to attempt anything else afterwards, the connection drops.
Is there a way to do this check "quietly", or suffering only "interruption", but without losing the connection,
When I install my application, it installs fine and everything works alongwith all the system level daemons but when I reboot the system, none of my daemons are getting launched and this happens only on MacOS 15x, on older version it is working fine.
In the system logs, I see that my daemons have been detected as legacy daemons by backgroundtaskmanagementd with Disposition [enabled, allowed, visible, notified]
2025-01-13 21:17:04.919128+0530 0x60e Default 0x0 205 0 backgroundtaskmanagementd: [com.apple.backgroundtaskmanagement:main] Type: legacy daemon (0x10010)
2025-01-13 21:17:04.919128+0530 0x60e Default 0x0 205 0 backgroundtaskmanagementd: [com.apple.backgroundtaskmanagement:main] Flags: [ legacy ] (0x1)
2025-01-13 21:17:04.919129+0530 0x60e Default 0x0 205 0 backgroundtaskmanagementd: [com.apple.backgroundtaskmanagement:main] Disposition: [enabled, allowed, visible, notified] (0xb)
But later, it backgroundtaskmanagementd decides to disallow it.
2025-01-13 21:17:05.013202+0530 0x32d Default 0x4d6 89 0 smd: (BackgroundTaskManagement) [com.apple.backgroundtaskmanagement:main] getEffectiveDisposition: disposition=[enabled, disallowed, visible, notified], have LWCR=true
2025-01-13 21:17:05.013214+0530 0x32d Error 0x0 89 0 smd: [com.apple.xpc.smd:all] Legacy job is not allowed to launch: <private> status: 2
Is there anything changed in latest Mac OS which is causing this issue? Also what does this status 2 means. Can someone please help with this error?
The plist has is true
I am developing a macOS non-interactive macOS application which does not show any ui.
i want to block main thread and do all the work on worker thread . Once done with work in worker thread, want to unblock main thread by exiting event loop to terminate application.
Because i dont want to show any UI or use any Foundation/Cocoa functionality, i am thinking of using CFRunLoop to block main thread from exiting until i finish my work in worker thread.
When i tried this in a project, I am able to finish work in worker thread after block main thread using CFRunLoop.
I also want this application to be a bundled application, which can be launched by double clicking on application bundle . But when i tried it in my xcode project by launching it using double clicking on application bundle, application keeps on toggling/bouncing in the dock menu with a status "Not responding". Although i am able to complete my work in worker thread.
import Foundation
let runLoop = CFRunLoopGetCurrent()
func workerTask() {
DispatchQueue.global().async {
print("do its work")
sleep(5) // do some work
print("calling exit event loop")
CFRunLoopStop(runLoop)
print ("unblocking main thread")
}
}
workerTask ()
// blocking main thread
print ("blocked main thread")
CFRunLoopRun()
print ("exit")
Why i am getting this application bouncing in doc menu behavior ? I tried by using NSApplicationMain instead of CFRunLoop in my project, in that case i didnt get this behavior .
Does NSApplicationMain does some extra work before starting NSRunLoop which i am not doing while using CFRunLoop, which is showing this toggling/Bouncing application icon in Dock menu ?
or Is this bouncing app icon issue is related to run loop i am using which is CFRunLoop ?
Note : If i dont use a bundled application and use a commandline application then i am able to do all steps in worker thread and exit main thread as i wanted after finishing my work . But i need to do all this in application which can be launched using double clicking (bundled applcation).
If not by using CFRunLoop, then how can i achive this ? - Create a application which shows no UI and do all work in worker thread while main thread is blocked. Once work is done unblock main thread and exit. And user should be able to launch application using double click the application icon.
We've seen a recent increase in background terminations:
blue - System Pressure
orange - Task Timeout
I'm trying to understand the increase in system-pressure terminations, since there's no corresponding increase in memory at suspension. Are there other system resources for which iOS will terminate an app?
Topic:
App & System Services
SubTopic:
Processes & Concurrency
Tags:
Organizer Window
Background Tasks
I have an app that uses background audio recording. From what others say, I have enabled the audio background mode to keep the audio session active, and this worked. But when submitting the app to the app store, the app was rejected because the audio background mode is only supposed to be used for audio playback.
How do I create this background mode while following Apple's guidelines?
I'm a developer using Lazarus Pascal, so converting ObjC and Swift comes with its challenges.
I'm trying to figure how to properly use SMAppService to add my application as a login item for the App Store.
I have learned that the old method (< macOS 13) uses a helper tool, included in the app bundle, which calls the now deprecated SMLoginItemSetEnabled. Now this is already quite a pain to deal with if you're not using XCode, not to mention converting the headers being rather complicated when you're not experienced with doing this.
The "new" method (as of macOS 13) is using SMAppService.
Can anyone explain how to use this? The documentation (for me anyway) is a not very clear about that and neither are examples that can be found all over the Internet.
My main question is:
Can I now use the SMAppService functions to add/remove a login item straight in my application, or is a helper tool still required?
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
I’m working with apple dispatch queue in C with the following design: multiple dispatch queues enqueue tasks into a shared context, and a dedicated dispatch queue (let’s call it dispatch queue A) processes these tasks. However, it seems this design has a memory visibility issue.
Here’s a simplified version of my setup:
I have a shared_context struct that holds:
task_lis: a list that stores tasks to be prioritized and run — this list is only modified/processed by dispatch queue A (a serially dispatch queue), so I don't lock around it.
cross_thread_tasks: a list that other queues push tasks into, protected by a lock.
Other dispatch queues call a function schedule_task that
locks and appends a new task to cross_thread_tasks
call dispatch_after_f() to schedule a process_task() on dispatch queue A
process_task() that processes the task_list and is repeatedly scheduled on dispatch queue A :
Swaps cross_thread_tasks into a local list (with locking).
Pushes the tasks into task_list.
Runs tasks from task_list.
Reschedules itself via dispatch_after_f().
Problem:
Sometimes the tasks pushed from other threads don’t seem to show up in task_list when process_task() runs. The task_list appears to be missing them, as if the cross-thread tasks aren’t visible. However, if the process_task() is dispatched from the same thread the tasks originate, everything works fine.
It seems to be a memory visibility or synchronization issue. Since I only lock around cross_thread_tasks, could it be that changes to task_list (even though modified on dispatch queue A only) are not being properly synchronized or visible across threads?
My questions
What’s the best practice to ensure shared context is consistently visible across threads when using dispatch queues? Is it mandatory to lock around all tasks? I would love to minimize/avoid lock if possible.
Any guidance, debugging tips, or architectural suggestions would be appreciated!
===============================
And here is pseudocode of my setup if it helps:
struct shared_data {
struct linked_list* task_list;
}
struct shared_context {
struct shared_data *data;
struct linked_list* cross_thread_tasks;
struct thread_mutex* lock; // lock is used to protect cross_thread_tasks
}
static void s_process_task(void* shared_context){
struct linked_list* local_tasks;
// lock and swap the cross_thread_tasks into a local linked list
lock(shared_context->lock)
swap(shared_context->cross_thread_tasks, local_tasks)
unlock(shared_context->lock)
// I didnt use lock to protect `shared_context->data` as they are only touched within dispatch queue A in this function.
for (task : local_tasks) {
linked_list_push(shared_context->data->task_list)
}
// If the `process_task()` block is dispatched from `schedule_task()` where the task is created, the `shared_context` will be able to access the task properly otherwise not.
for (task : shared_context->data->task_list) {
run_task_if_timestamp_is_now(task)
}
timestamp = get_next_timestamp(shared_context->data->task_list)
dispatch_after_f(timestamp, dispatch_queueA, shared_context, process_task);
}
// On dispatch queue B
static void schedule_task(struct task* task, void* shared_context) {
lock(shared_context->lock)
push(shared_context->cross_thread_tasks, task)
unlock(shared_context->lock)
timestamp = get_timestamp(task)
// we only dispatch the task if the timestamp < 1 second. We did this to avoid the dispatch queue schedule the task too far ahead and prevent the shutdown process. Therefore, not all task will be dispatched from the thread it created.
if(timestamp < 1 second)
dispatch_after_f(timestamp, dispatch_queueA, shared_context, process_task);
}
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.
For this code:
let status = try await container.accountStatus()
Seeing this error:
2025-05-08 15:32:00.945731-0500 localhost myAgent[2661]: (myDaemon.debug.dylib) [com.myDaemon.cli:networking] Error Domain=CKErrorDomain Code=6 "Error connecting to CloudKit daemon. This could happen for many reasons, for example a daemon exit, a device reboot, a race with the connection inactivity monitor, invalid entitlements, and more. Check the logs around this time to investigate the cause of this error." UserInfo={NSLocalizedDescription=Error connecting to CloudKit daemon. This could happen for many reasons, for example a daemon exit, a device reboot, a race with the connection inactivity monitor, invalid entitlements, and more. Check the logs around this time to investigate the cause of this error., CKRetryAfter=5, CKErrorDescription=Error connecting to CloudKit daemon. This could happen for many reasons, for example a daemon exit, a device reboot, a race with the connection inactivity monitor, invalid entitlements, and more. Check the logs around this time to investigate the cause of this error., NSUnderlyingError=0x600001bfc270 {Error Domain=NSCocoaErrorDomain Code=4099 UserInfo={NSDebugDescription=
I initially started the this process as System Daemon to see what would happen (which obviously does not have CloudKit features). Then moved it back to /Library/LaunchAgents/ and can't get rid of that error.
I see also following message from CloudKit daemon:
Ignoring failed attempt to get container proxy for <private>: Error Domain=NSCocoaErrorDomain Code=4099 UserInfo={NSDebugDescription=<private>}
Automatically retrying getting container proxy due to error for <private>: Error Domain=NSCocoaErrorDomain Code=4099 UserInfo={NSDebugDescription=<private>}
XPC connection interrupted for <private>
And this error for xpc service:
[0x130e074b0] failed to do a bootstrap look-up: xpc_error=[3: No such process]
If I start the same cli process directly from XCode, then it works just fine.
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!