How can you force cancel a task that doesn't need cleanup and doesn't check for cancellation?
If this cannot be done, would this be a useful addition to Swift?
Here is the situation:
The async method doesn't check for cancellation since it is not doing anything repetively (for example in a loop). For example, the method may be doing "try JSONDecoder().decode(Dictionary<String, ...>.self, from: data)" where data is a large amount.
The method doesn't need cleanup.
I would like the force cancellation to throw an error. I am already handling errors for the async method.
My intended situation if that the user request the async method to get some JSON encoded data, but since it is taking longer that they are willing to wait, they would tap a cancellation button that the app provides.
Processes & Concurrency
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Hi, I have been recently debugging the BGContinuedProcessingTask API and encountered some of the following issues. I hope you can provide some answers:
First, let me explain my understanding of this API. I believe its purpose is to allow an app to trigger tasks that can be represented with progress indicators and require a certain amount of time to complete.
After entering the background, these tasks can continue to be completed through the BGContinuedProcessingTask, preventing the system from terminating them before they are finished.
In the launchHandler of the registration process, we only need to do a few things:
Determine whether the actual business processing is still ongoing.
Update the progress, title, and subtitle.
Handle the expirationHandler.
Set the task as completed.
Here are some issues I encountered during my debugging process:
After I called register and submit, the BGContinuedProcessingTask could not be triggered. The return values from my API calls were all normal.
I tried different device models, and some could trigger the task normally, such as the 15 Pro Max and 12 Pro Max. However, there were also some models, such as the 17 Pro, 15 Pro, and 15, that could not trigger the task properly. Moreover, there was no additional error information to help locate the issue.
The background task failed unexpectedly, but my app was still running normally. As I mentioned above, my launchHandler only retrieves the actual business status and updates it.
If a background task fails unexpectedly while the app is still running normally, it can mislead users and degrade the user experience of the app.
Others have also mentioned the issue of inconsistent behavior on devices that do not support Dynamic Island. On devices that support Dynamic Island,
when a task is triggered in the foreground, the app does not immediately display a pop-up notification within the app. However, on devices that do not support Dynamic Island,
the app directly displays a pop-up notification within the app, and this notification does not disappear when switching between different screens within the same app.
The user needs to actively swipe up to dismiss it. I think this experience is too intrusive for users. I would like to know whether this will be maintained in the future or if there is a plan to fix it.
On devices that do not support Dynamic Island, using the beta version 26.1 of the system,
if the system is in dark mode but the app triggers a business interface in white, the pop-up notification will have the same color as the current page, making it difficult to read the content inside the pop-up.
Users can actively stop background tasks by using the stop button, or the system can also stop tasks automatically when resources are insufficient or when a task is abnormal.
However, according to the current API, all these actions are triggered through the expirationHandler.
Currently, there is no way to distinguish whether the task was stopped by the user, by the system due to resource insufficiency, or due to an abnormal task.
I would like to know whether there will be more information provided in the future to help distinguish these different scenarios.
I believe that the user experience issues mentioned in points 2 and 3 are the most important. Please help to answer the questions and concerns above. Thank you!
i am trying to create a daemon with xpc for my app by referring to https://github.com/alienator88/HelperToolApp but i keep getting XPC remote proxy error: Couldn’t communicate with a helper application. All the identifiers all correct but the helper code is not reached.
On macOS 15.7.1 I'm trying to install an XPC service outside the app (Developer ID). It mostly seems to go ok, but when I set Launch Constraints on Responsible, AMFI complains of a violation, saying the service is responsible for itself, and fails to launch. Removing that constraint (or adding the service itself to the constraint) works fine.
The service is an optional download, and installed to /Users/Shared with a LaunchAgent specifying the MachService. The service is correctly launched and seems to pass all codesigning, notarization, and other checks, but the Responsible isn't set to the "calling" app.
Is this broken, or working as intended?
Topic:
App & System Services
SubTopic:
Processes & Concurrency
Tags:
XPC
Code Signing
Developer ID
Service Management
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);
}
Issue:
Background downloads using the flutter_downloader package work perfectly in debug mode and release mode when run directly from Xcode (plugged in).
However, when I create an archive build and install the app separately (via TestFlight or direct IPA install), the background download stops working as soon as the app is minimized.
✅ What I’ve already done
Info.plist
<key>UIBackgroundModes</key>
<array>
<string>remote-notification</string>
<string>fetch</string>
<string>processing</string>
<string>audio</string>
<string>push-to-talk</string>
</array>
AppDelegate.swift
import UIKit
import Flutter
import Firebase
import flutter_downloader
import BackgroundTasks
@main
@objc class AppDelegate: FlutterAppDelegate {
static let backgroundChannel = "com.example.app/background_service"
private var backgroundCompletionHandler: (() -> Void)?
override func application(
_ application: UIApplication,
didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
) -> Bool {
FirebaseApp.configure()
GeneratedPluginRegistrant.register(with: self)
FlutterDownloaderPlugin.setPluginRegistrantCallback(registerPlugins)
if #available(iOS 10.0, *) {
UNUserNotificationCenter.current().delegate = self
}
if #available(iOS 13.0, *) {
registerBackgroundTask()
}
return super.application(application, didFinishLaunchingWithOptions: launchOptions)
}
@available(iOS 13.0, *)
private func registerBackgroundTask() {
BGTaskScheduler.shared.register(
forTaskWithIdentifier: "com.example.app.process_download_queue",
using: nil
) { [weak self] task in
guard let self = self else { return }
self.handleDownloadQueueTask(task: task as! BGProcessingTask)
}
}
@available(iOS 13.0, *)
private func handleDownloadQueueTask(task: BGProcessingTask) {
scheduleNextDownloadTask()
let headlessEngine = FlutterEngine(name: "BackgroundTaskEngine", project: nil, allowHeadlessExecution: true)
headlessEngine.run()
let channel = FlutterMethodChannel(
name: AppDelegate.backgroundChannel,
binaryMessenger: headlessEngine.binaryMessenger
)
task.expirationHandler = {
channel.invokeMethod("backgroundTaskExpired", arguments: nil)
}
channel.invokeMethod("processNextInBackground", arguments: nil) { result in
task.setTaskCompleted(success: (result as? Bool) ?? false)
}
}
override func application(
_ application: UIApplication,
handleEventsForBackgroundURLSession identifier: String,
completionHandler: @escaping () -> Void
) {
self.backgroundCompletionHandler = completionHandler
super.application(application, handleEventsForBackgroundURLSession: identifier, completionHandler: completionHandler)
}
override func applicationDidEnterBackground(_ application: UIApplication) {
if #available(iOS 13.0, *) {
scheduleNextDownloadTask()
}
}
@available(iOS 10.0, *)
override func userNotificationCenter(
_ center: UNUserNotificationCenter,
willPresent notification: UNNotification,
withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void
) {
if #available(iOS 14.0, *) {
completionHandler([.list, .banner, .badge, .sound])
} else {
completionHandler([.alert, .badge, .sound])
}
}
@available(iOS 10.0, *)
override func userNotificationCenter(
_ center: UNUserNotificationCenter,
didReceive response: UNNotificationResponse,
withCompletionHandler completionHandler: @escaping () -> Void
) {
completionHandler()
}
}
// MARK: - Helper
@available(iOS 13.0, *)
func scheduleNextDownloadTask() {
let request = BGProcessingTaskRequest(identifier: "com.example.app.process_download_queue")
request.requiresNetworkConnectivity = true
request.requiresExternalPower = false
request.earliestBeginDate = Date(timeIntervalSinceNow: 60)
do {
try BGTaskScheduler.shared.submit(request)
print("BGTask: Download queue processing task scheduled successfully.")
} catch {
print("BGTask: Could not schedule download queue task: \(error)")
}
}
private func registerPlugins(registry: FlutterPluginRegistry) {
if !registry.hasPlugin("FlutterDownloaderPlugin") {
FlutterDownloaderPlugin.register(with: registry.registrar(forPlugin: "FlutterDownloaderPlugin")!)
}
}
🧩 Observations
Background download works correctly when:
The app is plugged in and run via Xcode (release/debug)
It stops working when:
The app is installed from an archived build (IPA/TestFlight) and minimized
All entitlements and background modes are properly added.
Provisioning profile includes required background modes.
❓Question
Is there any known limitation or signing difference between Xcode run and archived release builds that could cause URLSession background tasks not to trigger?
Has anyone faced a similar issue when using flutter_downloader on iOS 13+ with BGTaskScheduler or URLSession background configuration?
Any help or working setup example for production/TestFlight would be appreciated.
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.
Hi,
I'm trying to create a launch daemon that uses XPC to receive requests from an unprivileged app. Ultimately both components will be written in Go. For now I'm trying to write a PoC in Objective-C to make sure I get everything right, so I'm compiling / signing from the CLI, and writing plist files by hand -- I'm not using XCode.
My current daemon code is pretty much the same as the boilerplate code that XCode generates when creating a new 'XPC Service':
#import <stdio.h>
#include <xpc/xpc.h>
int main(int argc, char *argv[]) {
xpc_rich_error_t error;
dispatch_queue_t queue = dispatch_queue_create("com.foobar.daemon", DISPATCH_QUEUE_SERIAL);
xpc_listener_t listener = xpc_listener_create(
"com.foobar.daemon",
queue,
XPC_LISTENER_CREATE_NONE,
^(xpc_session_t _Nonnull peer) {
xpc_session_set_incoming_message_handler(peer, ^(xpc_object_t _Nonnull message) {
int64_t firstNumber = xpc_dictionary_get_int64(message, "firstNumber");
int64_t secondNumber = xpc_dictionary_get_int64(message, "secondNumber");
// Create a reply and send it back to the client.
xpc_object_t reply = xpc_dictionary_create_reply(message);
xpc_dictionary_set_int64(reply, "result", firstNumber + secondNumber);
xpc_rich_error_t replyError = xpc_session_send_message(peer, reply);
if (replyError) {
printf("Reply failed, error: %s", xpc_rich_error_copy_description(replyError));
}
});
},
&error);
if (error != NULL) {
printf("ERROR: %s\n", xpc_rich_error_copy_description(error));
exit(1);
}
printf("Created listener: %s", xpc_listener_copy_description(listener));
// Resuming the serviceListener starts this service. This method does not return.
dispatch_main();
return 0;
}
I'm compiling, signing and installing my daemon with the following commands:
build_foobar() {
clang -Wall -x objective-c -o com.foobar.daemon poc/main.m
codesign --force --verify --verbose --options=runtime \
--identifier="com.foobar.daemon" \
--sign="Mac Developer: Albin Kerouanton (XYZ)" \
--entitlements=poc/entitlements.plist \
com.foobar.daemon
}
install_foobar() {
sudo cp com.foobar.daemon /Library/PrivilegedHelperTools/com.foobar.daemon
sudo cp poc/com.foobar.daemon.plist /Library/LaunchDaemons/com.foobar.daemon.plist
sudo launchctl bootout system/com.foobar.daemon || true
sudo launchctl bootstrap system /Library/LaunchDaemons/com.foobar.daemon.plist
}
Here's the content of my entitlements.plist file:
<?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>com.apple.application-identifier</key>
<string>ABCD.com.foobar.daemon</string>
</dict>
</plist>
And finally, here's my launchd plist file:
<?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.foobar.daemon</string>
<key>Program</key>
<string>/Library/PrivilegedHelperTools/com.foobar.daemon</string>
<key>ProgramArguments</key>
<array>
<string>/Library/PrivilegedHelperTools/com.foobar.daemon</string>
</array>
<key>RunAtLoad</key>
<false/>
<key>StandardOutPath</key>
<string>/tmp/com.foobar.daemon.out.log</string>
<key>StandardErrorPath</key>
<string>/tmp/com.foobar.daemon.err.log</string>
<key>Debug</key>
<true/>
</dict>
</plist>
Whenever I start my service using sudo launchctl start com.foobar.daemon, it exits with the following error message:
ERROR: Unable to activate listener: failed at listener activation with error 1 - Operation not permitted
System logs don't show anything interesting -- they're just repeating the same error message. I tried to add / remove some properties from both the entitlement and the launchd plist file but to no avail.
Any idea what's going wrong?
I am building an app that uses the SMAppService to register a LaunchDaemon that is bundled with my .app. I've got a priming flow created which walks the user through approving the service so that it will start on login.
However, I need to also be able to upgrade this background service if the user updates the app. To do this, I think I need to call unregisterAndReturnError and then registerAndReturnError.
From my testing, this seems to work correctly, but I have a concern. Will the user ever be prompted to re-authorize the LaunchDaemon that I am registering? If so, under what circumstances will that happen, and what does it look like (so that I can guide the user through it)?
Just trying to understand the documentation.
Obviously, we can send a request to the service to return all the data at once. Can the data arrive in pieces, involving either multiple async callbacks or a Combine Publisher?
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.
Is the title possible ? I tried [[thread valueForKey:@"_private"] valueForKey:@"tid"] but the tid was not kvc compliant. private apis are alright because this is just for testing remote process thread creation. I already have a working method but it has hardcoded assembly so you can't do anything else.
this question is mainly for Quinn (figured he may know something about this)
Hello, I'm developing a Mac application that uses a network extension. I'm trying to implement XPC to pass data between my main app and system extension and I'm using the SimpleFirewall demo app as a guide to do this. One thing I can't understand is how the ViewController in the SimpleFirewall main app has access to the class IPCConnection in the SimpleFirewallExtension without it being public and without SimpleFirewallExtension being imported in ViewController.
Topic:
App & System Services
SubTopic:
Processes & Concurrency
Tags:
XPC
System Extensions
Network Extension
iOS BGProcessingTask + Background Upload Not Executing Reliably on TestFlight (Works in Debug)
Description:
We are facing an issue with BGTaskScheduler and BGProcessingTask when trying to perform a background audio-upload flow on iOS. The behavior is inconsistent between Debug builds and TestFlight (Release) builds.
Summary of the Problem
Our application records long audio files (up to 1 hour) and triggers a background upload using:
BGTaskScheduler
BGProcessingTaskRequest
Background URLSession (background with identifier)
URLSession background upload task + AppDelegate.handleEventsForBackgroundURLSession
In Debug mode (Xcode → Run on device), everything works as expected:
BGProcessingTask executes
handleEventsForBackgroundURLSession fires
Background URLSession continues uploads reliably
Long audio files successfully upload even when the app is in background or terminated
However, in TestFlight / Release mode, the system does not reliably launch the BGProcessingTask or Background URLSession events.
Technical Details
We explicitly register BGTaskScheduler:
BGTaskScheduler.shared.register(
forTaskWithIdentifier: "example.background.process",
using: nil
) { task in
self.handleBackgroundProcessing(task: task as! BGProcessingTask)
}
We schedule it using:
let request = BGProcessingTaskRequest(identifier: "example.background.process")
request.requiresNetworkConnectivity = true
request.requiresExternalPower = false
try BGTaskScheduler.shared.submit(request)
We also use Background URLSession:
let config = URLSessionConfiguration.background(withIdentifier: sessionId)
config.sessionSendsLaunchEvents = true
config.isDiscretionary = false
AppDelegate.handleEventsForBackgroundURLSession is implemented correctly and works in Debug.
Issue Observed (TestFlight Only)
In TestFlight builds:
BGProcessingTask rarely triggers, or the system marks it as NO LONGER RUNNING.
Background upload tasks sometimes never start or complete.
No logs appear from our BGProcessingTask handler.
system logs show messages like:
NO LONGER RUNNING bgProcessing-example.background.process
Tasks running in group [com.apple.dasd.defaultNetwork] are 1!
This occurs most frequently for large audio uploads (30–60 minutes), while small files behave normally.
What We Have Verified
Proper Info.plist values:
Permitted background modes: processing, audio, fetch
BGTaskSchedulerPermittedIdentifiers contains our identifier
BGProcessingTask is being submitted successfully (no errors)
App has microphone permission + background audio works
Device plugged/unplugged doesn’t change outcome
Key Question for Apple
We need clarification on:
Why BGProcessingTask behave differently between Debug and TestFlight builds?
Are there additional restrictions or heuristics (related to file size, CPU usage, runtime, network load, or power constraints) that cause BGProcessingTask to be throttled or skipped in Release/TestFlight?
How can we guarantee a background upload continues reliably for large files (100MB–500MB) on TestFlight and App Store builds?
Is there an Apple-recommended pattern to combine BGProcessingTask + Background URLSession for long-running uploads?
Expected Result
Background uploads should continue reliably for long audio files (>30 minutes) when the app goes to background or is terminated, in the same way they currently function in Debug builds.
Topic:
App & System Services
SubTopic:
Processes & Concurrency
Tags:
iOS
Background Tasks
Foundation
CFNetwork
I posted here https://developer.apple.com/forums/thread/805554?page=1#867766022 but posting again for visibility (and let me know how I can file a bug)
There was a response in that thread that said you could use the childProgress system to help updating progresses to keep the backgroundTask alive.
What I've found is that using childProgresses results in more terminations than if you just updated the progress directly.
Here is my setups to test this
A BGContinuedProcessingTask that uses URLSessions to upload, and registers the task.progress with the Urlsession Progress
Same, but the task.progress gets updated via a UrlSession Callback
The second is MUCH more stable out in the field in cellular settings, the first fails extremely frequently.
My suspicion is that in the documentation here https://developer.apple.com/documentation/foundation/progress#Reporting-Progress-for-Multiple-Operations
it explicitly states
The completedUnitCount property for a containing progress object only updates when the suboperation is 100% complete. The fractionCompleted property for a containing progress object updates continuously as work progresses for all suboperations.
I wonder if BGContinuedProcessingTask is only looking at completedUnitCount for progress, and not fractionCompleted?
In either case, I would love to use the childProgresses because there are bugs with retries by updating the progress manually, so would love some help resolving this, Thanks!
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.
After logging in to the main App, turn on screen recording, then switch to the interface of another App to perform operations. After about ten-odd minutes, when returning to the main App, it was found that the app was forcefully quit by the system, and subsequent operations could not be carried out.
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
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?
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?
Topic:
App & System Services
SubTopic:
Processes & Concurrency
Tags:
Files and Storage
App Sandbox
XPC