Swift Concurrency Resources: Forums tags: Concurrency The Swift Programming Language > Concurrency documentation Migrating to Swift 6 documentation WWDC 2022 Session 110351 Eliminate data races using Swift Concurrency — This ‘sailing on the sea of concurrency’ talk is a great introduction to the fundamentals. WWDC 2021 Session 10134 Explore structured concurrency in Swift — The table that starts rolling out at around 25:45 is really helpful. Swift Async Algorithms package Swift Concurrency Proposal Index DevForum post Why is flow control important? forums post Dispatch Resources: Forums tags: Dispatch Dispatch documentation — Note that the Swift API and C API, while generally aligned, are different in many details. Make sure you select the right language at the top of the page. Dispatch man pages — While the standard Dispatch documentation is good, you can still find some great tidbits in the man pages. See Reading UNIX Manual Pages. Start by reading dispatch in section 3. WWDC 2015 Session 718 Building Responsive and Efficient Apps with GCD [1] WWDC 2017 Session 706 Modernizing Grand Central Dispatch Usage [1] Avoid Dispatch Global Concurrent Queues forums post Waiting for an Async Result in a Synchronous Function forums post Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" [1] These videos may or may not be available from Apple. If not, the URL should help you locate other sources of this info.

Let's image that someone wants to use a background service to keep track of FSEvents activity, at the file level (a firehose, some might say). I choose this example, to indicate the volume and rate of data transmission in question. I'm not creating a front-end for FSEvents data, but my background service may generate data at a similar pace. The service runs off of user defined document/s that specify the FSEvent background filtering to be applied. Those that match get stored into a database. But filters can match on almost all the data being emitted by FSEvents. The user decides to check on the service's activity and database writes by launching a GUI that sends requests to the background service using XPC. So the GUI can request historic data from a database, but also get a real-time view of what FS events the service is busy filtering. So it's a client-server approach, that's concerned with monitoring an event stream over XPC. I understand XPC is a request/response mechanism, and I might look into using a reverse connection here, but my main concern is one of performance. Is XPC capable of coping with such a high volume of data transmision? Could it cope with 1000s of rows of table data updates per second sent to a GUI frontend? I know there are streaming protocol options that involve a TCP connection, but I really want to stay away from opening sockets.

My load average on a largely idle system is around 22, going up to 70 or so periodically; SSMenuAgent seems to be consuming lots of CPU (and, looking at spindump, it certainly seems busy), but... it's not happening on any other system whose screens I am observing. (Er, I know about load average limitations, the process is also consuming 70-98% CPU according to both top and Activity Monitor.) Since this machine (although idle) has our network extension, I'm trying to figure out if this is due to that, or of this is generally expected. Anyone?

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.

Hello Apple Developer Community, I am developing a medical app that is classified as Class B according to FDA regulations. The app connects to a medical device using Bluetooth Low Energy (BLE) to collect critical medical data such as ECG readings. To ensure accurate data collection and maintain the quality of the medical readings, the app needs to wake up every five minutes in the background and perform tasks for approximately 30 seconds. I understand that iOS has strict limitations on background execution to preserve battery and system performance. However, due to the medical nature of the app and the need for periodic data collection, I am seeking guidance on the following: If I can provide documentation that the app is associated with an FDA-approved Class B medical device, would Apple allow more lenient background task execution policies? Are there specific APIs, such as BackgroundTasks, CoreBluetooth, or other recommended strategies, that could help me achieve this behavior reliably? Is there a process to apply for an exception or special consideration for medical apps that require periodic background activity? Any insights or recommendations would be greatly appreciated. Thank you!

When using the old withTaskCancellationHandler(operation:onCancel:isolation:) to run background tasks, you were notified that the background task gets cancelled via the handler being called. SwiftUI provides the backgroundTask(_:action:) modifier which looks quite handy. However how can I check if the background task will be cancelled to avoid being terminated by the system? I have tried to check that via Task.isCancelled but this always returns false no matter what. Is this not possible when using the modifier in which case I should file a bug report? Thanks for your help

I'm using Swift 6 and tasks to concurrently process multiple PDF files for rendering, and it's working well. But currently I'm manually limiting the number of simultaneous tasks to 2 out of fear that the system might run many tasks concurrently without having enough RAM to do the PDF processing. Testing on a variety of devices, I've tried increasing the task limit and haven't seen any crashes, but I'm quite concerned about the possibility. Any given device might be using a lot of RAM at any moment, and any given PDF might strain resources more than the average PDF. Is there a recommended technique for handling this kind of scenario? Should I not worry about it and just go ahead and start a high number of tasks, trusting that the system won't run too many concurrently and therefore won't run out of RAM?

I'm developing a macOS application that tracks the duration of a user's session using a timer, which is displayed both in the main window and in an menu bar extra view. I have a couple of questions regarding the timer's behavior: What happens to the timer if the user closes the application's window (causing the app to become inactive) but does not fully quit it? Does the timer continue to run, pause, or behave in some other way? Will the app nap feature stop the timer when app is in-active state?

Hi, I’m using a Local Push Connectivity Extension and encountering an issue with DispatchSourceTimer. In my extension, I create a DispatchSourceTimer that is supposed to fire every 1 second. It works as expected at first. However, when the app is in the foreground and the device is locked, the timer eventually stops firing after 1–3 hours. The extension process is still alive, and no errors are thrown Has anyone experienced this behavior? Is this a known limitation for timers inside NEAppPushProvider, or is the extension being deprioritized silently by the system? Any insights or suggestions would be greatly appreciated. Thanks!

I have followed these steps as mentioned in this link :(https://developer.apple.com/forums/thread/721737) My projects app bundle structure is like this : TWGUI.app TWGUI.app/Contents TWGUI.app/Contents/_CodeSignature TWGUI.app/Contents/_CodeSignature/CodeResources TWGUI.app/Contents/MacOS TWGUI.app/Contents/MacOS/TWAgent TWGUI.app/Contents/MacOS/TWGUI TWGUI.app/Contents/Resources TWGUI.app/Contents/Library TWGUI.app/Contents/Library/LaunchAgents TWGUI.app/Contents/Library/LaunchAgents/com.example.TWGUI.agent.plist TWGUI.app/Contents/Info.plist TWGUI.app/Contents/PkgInfo TWGUI is my main GUI App , i which i want to embed TWAgent (a command line tool target) and register it using SMAppServices so that launchd can launch it. In TWGUI, code for registering to launchd using SMAppServices is structure as follow : import SwiftUI import ServiceManagement struct ContentView: View { let agent = SMAppService.agent(plistName: "com.example.TWGUI.agent.plist") var body: some View { VStack { Button("Register Agent") { RegisterAgent () } .padding() Button("Unregister Agent") { UnregisterAgent () } .padding() } } func RegisterAgent() { DispatchQueue.global(qos: .background).async { do { print("Registering Agent. Status: \(agent.status.rawValue)") try agent.register() print("Agent registered") } catch { print("Failed to register agent: \(error)") } } } func UnregisterAgent() { DispatchQueue.global(qos: .background).async { do { print("Unregistering Agent. Status: \(agent.status.rawValue)") try agent.unregister() print("Agent unregistered") } catch { print("Failed to unregister agent: \(error)") } } } } com.example.TWGUI.agent.plist : <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs$ <plist version="1.0"> <dict> <key>Label</key> <string>com.example.TWGUI.agent</string> <key>ProgramArguments</key> <array> <string>Contents/MacOS/TWAgent</string> </array> <key>RunAtLoad</key> <true/> <key>KeepAlive</key> <true/> </dict> </plist> I have used ProgramArguements instead of using Program in above plist because i was getting this error when i was using Program earlier : Registering Agent. Status: 3 Failed to register agent: Error Domain=SMAppServiceErrorDomain Code=111 "Invalid or missing Program/ProgramArguments" UserInfo={NSLocalizedFailureReason=Invalid or missing Program/ProgramArguments} TWGUI apps Info.plist is : <?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>BuildMachineOSBuild</key> <string>23C71</string> <key>CFBundleDevelopmentRegion</key> <string>en</string> <key>CFBundleExecutable</key> <string>TWGUI</string> <key>CFBundleIdentifier</key> <string>com.example.TWAgent</string> <key>CFBundleInfoDictionaryVersion</key> <string>6.0</string> <key>CFBundleName</key> <string>TWGUI</string> <key>CFBundlePackageType</key> <string>APPL</string> <key>CFBundleShortVersionString</key> <string>1.0</string> <key>CFBundleSupportedPlatforms</key> <array> <string>MacOSX</string> </array> <key>CFBundleVersion</key> <string>1</string> <key>DTCompiler</key> <string>com.apple.compilers.llvm.clang.1_0</string> <key>DTPlatformBuild</key> <string></string> <key>DTPlatformName</key> <string>macosx</string> <key>DTPlatformVersion</key> <string>14.2</string> <key>DTSDKBuild</key> <string>23C53</string> <key>DTSDKName</key> <string>macosx14.2</string> <key>DTXcode</key> <string>1510</string> <key>DTXcodeBuild</key> <string>15C65</string> <key>LSMinimumSystemVersion</key> <string>14.2</string> </dict> </plist> TWAgent target has main.swift file which does this : import Foundation let startTime = CFAbsoluteTimeGetCurrent() func logTimeSinceStart() { let elapsedTime = CFAbsoluteTimeGetCurrent() - startTime NSLog("Time since program started: \(elapsedTime) seconds") } func startLoggingTime() { Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { _ in logTimeSinceStart() } } // Start logging time startLoggingTime() // Keep the run loop running CFRunLoopRun() I followed these exact same steps in another project earlier and my agent was getting registered, although i lost that project due to some reasons. But now i am getting this error when i am registering or unregistering agent using SMAppServices from the code above : Registering Agent. Status: 3 Failed to register agent: Error Domain=SMAppServiceErrorDomain Code=1 "Operation not permitted" UserInfo={NSLocalizedFailureReason=Operation not permitted} I tried diffrent fixes for like this : Moved app bundle to /applications folder Gave permission for full disc access to this app . Code sign again (both agent and TWGUI ... But nothing seems to work , getting same error. I tried to launch agent using : Launchctl load com.example.TWGUI.agent.plist and it worked , so there is no issue with my plist implementation. Can someone help me understand how can i solve this issue ? or if i am following right steps ? Can give steps need to follow to implement this and steps so that i can register and start my agent using SMAppServices? And i also tried the project give in apples official documentation : [https://developer.apple.com/documentation/servicemanagement/updating-your-app-package-installer-to-use-the-new-service-management-api) but got same error in this project as well .

I'm working on implementing file moving with NSFileCoordinator. I'm using the slightly newer asynchronous API with the NSFileAccessIntents. My question is, how do I go about notifying the coordinator about the item move? Should I simply create a new instance in the asynchronous block? Or does it need to be the same coordinator instance? let writeQueue = OperationQueue() public func saveAndMove(data: String, to newURL: URL) { let oldURL = presentedItemURL! let sourceIntent = NSFileAccessIntent.writingIntent(with: oldURL, options: .forMoving) let destinationIntent = NSFileAccessIntent.writingIntent(with: newURL, options: .forReplacing) let coordinator = NSFileCoordinator() coordinator.coordinate(with: [sourceIntent, destinationIntent], queue: writeQueue) { error in if let error { return } do { // ERROR: Can't access NSFileCoordinator because it is not Sendable (Swift 6) coordinator.item(at: oldURL, willMoveTo: newURL) try FileManager.default.moveItem(at: oldURL, to: newURL) coordinator.item(at: oldURL, didMoveTo: newURL) } catch { print("Failed to move to \(newURL)") } } }

Hi, I have some questions regarding the Background Assets Extension and DeviceCheck framework. Goal: Ensure that only users who have purchased the app can access the server's API without any user authentication using for example DeviceCheck framework and within a Background Assets Extension. My app relies on external assets, which I'm loading using the Background Assets Extension. I'm trying to determine if it's possible to obtain a challenge from the server and send a DeviceCheck assertion during this process within the Background Assets Extension. So far, I only receive session-wide authentication challenges—specifically NSURLAuthenticationMethodServerTrust in the Background Assets Extensio. I’ve tested with Basic Auth (NSURLAuthenticationMethodHTTPBasic) just for experimentation, but the delegate func backgroundDownload( _ download: BADownload, didReceive challenge: URLAuthenticationChallenge ) async -> (URLSession.AuthChallengeDisposition, URLCredential?) is never called with that authentication method. It seems task-specific challenges aren't coming through at all. Also, while the DCAppAttestService API appears to be available on macOS, DCAppAttestService.isSupported always returns false (in my testing), which suggests it's not actually supported on macOS. Can anyone confirm if that’s expected behavior?

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?

When I search, it's always people trying to do stuff in the background. I want my app to only do stuff when it is active. And this post https://developer.apple.com/forums/thread/685525 seems to have prevented replies from the start. Which means it's just a documentation page and does not belong in the discussion forums at all, because it prevents all discussion.

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!

Will App be terminated or suspended when updating to incremental version from app store?

We are currently developing a VoIP application that supports Local Push extention. I would like to ask for your advice on how the extension works when the iPhone goes into sleep mode. Our App are using GCD (Grand Central Dispatch) to perform periodic processing within the extension, creating a cycle by it. [sample of an our source] class LocalPushProvider: NEAppPushProvider { let activeQueue: DispatchQueue = DispatchQueue(label: "com.myapp.LocalPushProvider.ActiveQueue", autoreleaseFrequency: .workItem) var activeSchecule: Cancellable? override func start(completionHandler: @escaping (Error?) -&gt; Void) { : self.activeSchecule = self.activeQueue.schedule( after: .init(.now() + .seconds(10)), // start schedule after 10sec interval: .seconds(10) // interval 10sec ) { self.activeTimerProc() } completionHandler(nil) } } However In this App that we are confirming that when the iPhone goes into sleep mode, self.activeTimerProc() is not called at 10-second intervals, but is significantly delayed (approximately 30 to 180 seconds). What factors could be causing the timer processing using GCD not to be executed at the specified interval when the iPhone is in sleep mode? Also, please let us know if there are any implementation errors or points to note. I apologize for bothering you during your busy schedule, but I would appreciate your response.

General: DevForums subtopic: App & System Services > Processes & Concurrency Processes & concurrency covers a number of different technologies: Background Tasks Resources Concurrency Resources — This includes Swift concurrency. Service Management Resources XPC Resources Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com"

Hi, I'm working on an application on MacOS. It contains a port-forward feature on TCP protocol. This application has no UI, but a local HTTP server where user can access to configure this application. I found that my application always exit for unknown purpose after running in backgruond for minutes. I think this is about MacOS's background process controlling. Source codes and PKG installers are here: https://github.com/burningtnt/Terracotta/actions/runs/16494390417

My app does really large uploads. Like several GB. We use the AWS SDK to upload to S3. It seemed like using BGContinuedProcessingTask to complete a set of uploads for a particular item may improve UX as well as performance and reliability. When I tried to get BGContinuedProcessingTask working with the AWS SDK I found that the task would fail after maybe 30 seconds. It looked like this was because the app stopped receiving updates from the AWS upload and the task wants consistent updates. The AWS SDK always uses a background URLSession and this is not configurable. I understand the background URLSession runs in a separate process from the app and maybe that is why progress updates did not continue when the app was in the background. Is it expected that BGContinuedProcessingTask and background URLSession are not really compatible? It would not be shocking since they are 2 separate background APIs. Would the Apple recommendation be to use a normal URLSession for this, in which case AWS would need to change their SDK? Or does Apple think that BGContinuedProcessingTask should just not be used with uploads? In other words use an upload specific API. Thanks!