General: DevForums tag: Background Tasks Background Tasks framework documentation UIApplication background tasks documentation ProcessInfo expiring activity documentation watchOS background execution documentation WWDC 2020 Session 10063 Background execution demystified — This is critical resource. Watch it! WWDC 2022 Session 10142 Efficiency awaits: Background tasks in SwiftUI iOS Background Execution Limits DevForums post UIApplication Background Task Notes DevForums post Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com"

Music app stops playing when switching to the background In apps that play music or music files, if you move to the home screen or run another app while the app is running, the music playback stops. Our app does not have the code to stop playing when switching to the background. We are guessing that some people experience this and others do not. We usually guide users to reboot their devices and try again. How can this phenomenon be improved in the code? Or is this a bug or error in the OS?

After the 'IdentificationAccepted' message, I sent 'RequestAppLaunch' with 'AppBundleID' and 'AppLaunchMethod'. However, the app isn't launched by the external accessory. I checked it with ATS and saw the error message: 'Error: accessory sent a message that the Apple device did not acknowledge during identification. Section: Section 28.2.2 Sent/Received iAP2 Control Session Messages. Source: Accessory Interface Specification R42.' Do you have any idea how to fix it? Thank you in advance.

Let's say I have a Task that I want to extend into the background with beginBackgroundTask(expirationHandler:). Furthermore, I'd like to leverage cooperative cancelation of subtasks when responding to the expiration handler. Unfortunately, the expirationHandler: closure parameter is not async, so I'm unable to do something like: actor MyTaskManagerOne { var backgroundID = UIBackgroundTaskIdentifier.invalid func start() { Task { let doTheWorkTask = Task { await self.doTheWork() } backgroundID = await UIApplication.shared.beginBackgroundTask { doTheWorkTask.cancel() // next line: compile error, since not an async context await doTheWorkTask.value // ensure work finishes up // next line: generates MainActor compilation warnings despite docs allowing it UIApplication.shared.endBackgroundTask(self.backgroundID) } await doTheWorkTask.value } } func doTheWork() async {} } So instead, I think I have to do something like this. It, however, generates runtime warnings, since I'm not directly calling endBackgroundTask(_:) at the end of the expirationHandler: actor MyTaskManagerTwo { var backgroundID = UIBackgroundTaskIdentifier.invalid func start() { Task { let doTheWorkTask = Task { await self.doTheWork() } backgroundID = await UIApplication.shared.beginBackgroundTask { doTheWorkTask.cancel() // 1. not calling endBackgroundTask here generates runtime warnings } await doTheWorkTask.value // 2. even though endBackgroundTask gets called // here (as long as my cooperative cancellation // implementations abort quickly in `doTheWork()`) await UIApplication.shared.endBackgroundTask(self.backgroundID) } } func doTheWork() async {} } As best I can tell, the MyTaskManagerTwo actor works and does not cause a watchdog termination (as long as cancellation is sufficiently fast). It is, however, producing the following runtime warning: Background task still not ended after expiration handlers were called: <_UIBackgroundTaskInfo: 0x302753840>: taskID = 2, taskName = Called by libswift_Concurrency.dylib, from <redacted>, creationTime = 9674 (elapsed = 28). This app will likely be terminated by the system. Call UIApplication.endBackgroundTask(_:) to avoid this. Is the runtime warning ok to ignore in this case?

I have a .app file that I want to run as a daemon. Now there are two ways of running .app as a daemon/agent in macOS. using .app file : I can specify this in the daemon plist as: <key>ProgramArguments</key> <array> <string>/usr/bin/open</string> <string>/Applications/myApp.app</string> </array> using unix exe within .app file <key>ProgramArguments</key> <array> <string>myApp.app/Content/MacOS/MyApp</string> </array> Basically I wanted to know what is the Apple recommendation on how we should be creating daemon plist. For point 2, is it appropriate to use the unix executable within bundle?Will it not cause any issue in the running application? Is will be helpful if there is some apple documentation to support this.

I am working on an app which is capturing photos and uploading them to a server. I have followed the URLSession configuration to properly support background transfers. However, I am now noticing that my photos are uploading way slower, even when the user has the app open and is interacting with the app. This is undesirable because the changes need to be reflected in real time to the server when the user is active in the app. Previously, when I was just using URLSession.shared.uploadTask with a completion handler, the photos uploaded right away in a matter of 1-2 seconds. Now it is taking 3-4 minutes per photo to upload. The photos are roughly 3mb in size each. I have tried setting the isDiscretionary property explicitly to false to no avail. Sometimes the users are without internet connection, which is why I wanted to use the background session (so that the uploads can be automatically retried by the system when the user connects back to the internet) So, in summary, I want the functionality of the background uploading (and to let the system retry when the user transitions from offline to online) however I also need realtime uploading when the user is interacting with the app. What is the preferred way to solve this problem?

I have developed a backup application in Java. In it, users can configure whether they want it to autostart or not. If they do, a plist file is being written to ~/Library/LaunchAgents so that my app starts at login. This works perfectly so far. I've not submitted it to the Mac App Store. But for that, it needed to be sandboxed. And with that, I had to add a "com.apple.security.temporary-exception.files.home-relative-path.read-write=/Library/LaunchAgents/" to my entitlements so that the plist file could still be written to ~/Library/LaunchAgents. However, they do not approve this. Is there another solution to launch my application at login? Must work with sandbox-mode Must work from Java/Shell/... (I found "SMAppService", but this seems only available in Swift/Objective-C)

Hello, I would like to implement the function of unsubscribe FCM topics that I was subscribing to when I received a specific push from the server. It was implemented through "willPresent" when the app was running, but I don't know how to do it when the app is not running. I activated the 'Background fetch' and 'Remote Notifications' options for now. const message = { notification: { title: 'FCM Topic UnSubscribe', body: 'TestTestTest', }, data: { payload: JSON.stringify(payloadJson) }, apns: { payload: { aps: { sound: 'default', 'mutable-content': 1, 'content-available': 1 } } }, topic: 'unsubscribe_topic', }; Test node code Payload contains the type of topic you want to unsubscribe from. And I added a function to receive push from didReceiveRemoteNotification and handle logic. But this doesn't work. Does Remote Notification (content-available) not work in iOS's Not running and Suspended state?? I'm also using the Notification Service Extension, is this related to it?

I created a macOS app that can run in foreground (NSApplicationActivationPolicyRegular) and in background (NSApplicationActivationPolicyAccessory) and can be launched by an Helper (Login Item) and run in background. I use XCode 15.3 (15E204a) on macOS 14.2.1 on a MacBook Pro 16", 2019, 2,3 GHz Intel Core i9 8 core. I archive my app, I notarize it for direct distribution then I save it to the /Applications folder. Then I delete my Debug app from …/Xcode/DerivedData/MyApp-dal…xu/Build/Products/Debug so I am sure I have one only copy of my app on the disk. I firstly launch my app as NSApplicationActivationPolicyRegular then I select my menu item "Set the app as Login Item". So I call SMAppService *service = [SMAppService loginItemServiceWithIdentifier:@"com.mydomain.Helper"]; I get a service.status == SMAppServiceStatusNotFound So I am stuck. I notice that my app doesn't show up in the System Preferences/Login Items/ "Allow Background" list. So on Terminal I run the command sudo sfltool resetbtm Now the "Allow Background" apps list is empty. Then I reboot. All the apps listed in "Allow Background" list reappear and are all turned "on". I turn them back off. My app is on the list too (turned "on" too). I leave it on. Now I can launch my app as NSApplicationActivationPolicyRegular, select again my menu item "Set the app as Login Item" and call SMAppService *service = [SMAppService loginItemServiceWithIdentifier:@"com.domain.Helper"]; Now I get a service.status == SMAppServiceStatusEnabled so I install the NSStatusItem and switch to background (NSApplicationActivationPolicyAccessory). I can logout and login and my app gets properly launched by the Helper and run in background. Everything works well. I guess I miss something, because I think this is not the way to distribute my app to the customers. I can't ask my customers to run the Terminal command sudo sfltool resetbtm, reboot then turn back "off" all the unwanted apps from the "Allow Background" list then turn my app "on". Furthermore, if I delete my app, it disappears from the "Allow Background" apps list, then if I copy it back to the /Applications folder, it doesn't show up yet in the "Allow Background" apps list. I have to invoke again the sudo sfltool resetbtm Terminal command, reboot… to see it in that list. I tried on 3 machines with macOS 14.2.1. Same result. I have read several articles and posts about NSApplicationActivationPolicyAccessory, SMAppService, but I didn't find my case. The Info.plist file of the Helper properly contains <key>LSBackgroundOnly</key><true/> <key>LSUIElement</key><true/> • What do I miss? • Why my app doesn't show up in the "Allow Background" apps list when I simply copy it within the /Applications folder?

Hi, We are developing an app for secure printing using a BLE RFID reader. What we'd like to accomplish is the ability for a user to walk away from the printer (BLE RFID reader) for any time period (10 mins, 1 hour, or 3 hours) with the app still running background mode but out of range from the RFID reader, and walks back to the printer (BLE RFID reader) and be able to connect to the reader thus enabling printing. We've noticed that when the phone is out of range from the BLE reader and phone auto-locks, the background scanning process is terminated after a few minutes. Is there a way to accomplish the above? Any help is appreciated. Thank you, Marlon

We've got a non-sandboxed app with a built-in daemon that does some root-privileged things for us on occasion. We're using the newest SMAppService APIs, using NSXPCConnections for communications, and generally things work as expected. The daemon is set up to terminate when the parent app terminates. Our app also has (and uses the daemon for) a self-update feature. Once the new app is downloaded, the daemon takes over, replaces the app in-place, terminates the old app and launches the new one. However, after this update, the daemon no longer works. Any other build & launch of the app will silently fail when trying to talk to the daemon. The XPC connection can be constructed as usual, no errors, the process goes along like it should app-side, but the daemon never actually launches and never responds. I can imagine there could be a few rules being broken here with the self-update and the built-in daemon, but what would they be and how can we work within the rules?

Hello, I have an iOS app and a companion watchOS app. Users record a workout on Apple Watch, the data for which is then transferred using both Watch Connectivity and Core Data + CloudKit (NSPersistentCloudKitContainer) to their iPhone, where it is processed and displayed. As users are recording the workout on their Apple Watch, when they finish and the transfer begins, their iPhone is often not reachable to immediately send the data using Watch Connectivity and they have no network connection (cellular or Wi-Fi). With Watch Connectivity I use transferFile from WCSession, which queues the file for transfer. With Core Data + Cloudkit I save the data and the export is queued. An undetermined amount of time may pass until the user returns to their iPhone or connects to Wi-Fi and most of the time neither of the transfer methods actually transfers the data until the user opens the watchOS app into the foreground, at which point the transfer happens immediately for both methods. I've tried a number of things already, without success, such as: Using sendMessage from WCSession to send an immediate message to the watchOS app when the iOS app returns to the foreground to try and wake the watchOS app up so it can complete the data transfer. On the watchOS app, after attempting to transfer the data, using downloadTask from URLSession to queue a background task to download something, in the hope that it would wake the watchOS app when network connectivity was restored and enable it to complete the data transfer. On the watchOS app, instead of saving the data using NSPersistentCloudKitContainer, using CKRecord and CKDatabase directly to save the data using userInitiated as the quality of service, in the hope that it would be exported once network connectivity was restored. Is there a way to trigger the watchOS app to transfer the data using Watch Connectivity or Core Data + CloudKit in the background when reachabillity or network connectivity is restored, even if the app may have been suspended by watchOS? Many Thanks, Alex

My app need a specific scene that play a video when my iPhone close to NFC Tags. and my app can read the data from NFC Tags, the data will tell us which kind of video can be play. I tried to write URLScheme or Universal Link in NFC Tags, but all this ways will pop up notifications. not launch my app and play a video, how can I design my app. please give me some advice, thanks!

I'd like to launch my APP via scanning NFC Tags In BackgroundMode. However, every time when I scan NFC tags, there always APP notification pops up, instead of opening APP directly. Please advise me how to skip the APP notification and directly launch APP.

Hello, as the title says, I am trying to access Bluetooth in a system daemon. I am running on MacOS Sonoma 14.5. When initializing Bluetooth, my daemon received Unauthorized state. I have tried to add my daemon in the system settings (System Preferences > Security & Privacy > Privacy > Bluetooth) "Allow applications to access Bluetooth" by adding the program executable path defined by the entry Program of my system daemon as suggested here: https://developer.apple.com/forums/thread/662459. But I am still having the issue. Writing a system daemon with Bluetooth is not my final goal. The bigger picture is the smartcard reader driver with Bluetooth access which as the same issue and the solution is probably related. I do not remember how but my smartcard reader driver use to work with Bluetooth but it does now with the same Unauthorized error. As far as I can see daemon and smartcard drivers does not have support for entitlement. Here are the logs for my sample system daemon: my_daemon [0x6000011b0000] activating connection: mach=true listener=false peer=false name=com.apple.server.bluetooth.le.att.xpc bluetoothd [0x7f804828e8a0] activating connection: mach=false listener=false peer=true name=com.apple.server.bluetooth.le.att.xpc.peer[76672].0x7f804828e8a0 bluetoothd Received XPC message "CBMsgIdCheckIn" from session "" bluetoothd Received XPC check-in from session "my_daemon-5555494498236e3b5e2e395b93c13af176769937-peripheral-76672-67" fAccessLevel 0 fProgrammaticPairing 0 fLimitedForMediaAccess 0 bluetoothd Access level is less than kXPCAccessLevelSystem for session "my_daemon-5555494498236e3b5e2e395b93c13af176769937-peripheral-76672-67". Restricted state operation not allowed bluetoothd Sending 'session attached' event for session "my_daemon-5555494498236e3b5e2e395b93c13af176769937-peripheral-76672-67" bluetoothd Attached session for "my_daemon-5555494498236e3b5e2e395b93c13af176769937-peripheral-76672-67" with session: 0x7f804802d1b0, session handle: 0xef8d0000 bluetoothd Registering peripheral session "my_daemon-5555494498236e3b5e2e395b93c13af176769937-peripheral-76672-67" with backgrounding: off, persistence: off (CBSR) restoreID: (null) bluetoothd Error getting Application State for <private>: <private>, 3 bluetoothd Error getting Application State for <private>: <private>, 3 bluetoothd Session "my_daemon-5555494498236e3b5e2e395b93c13af176769937-peripheral-76672-67" tccRequired : 1 bluetoothd ReadyForTCC. TCC required:1 fLimitedForMediaAccess:0 fDeviceAccessForMediaExtension:0 bluetoothd Session "my_daemon-5555494498236e3b5e2e395b93c13af176769937-peripheral-76672-67" : needsRestrictedStateOperation = 0, overrideRestrictedState = 0 , denylistMode = 0, receivesControllerBTClockEvents=0 my_daemon Received CBMsgIdReadyForTCC my_daemon Running performTccCheck CBManager tccAvail 1, tccRequired 1 my_daemon TCC required my_daemon [0x6000011b8000] activating connection: mach=true listener=false peer=false name=com.apple.tccd my_daemon [0x6000011b8000] failed to do a bootstrap look-up: xpc_error=[3: No such process] my_daemon [0x6000011b8000] invalidated after a failed init my_daemon send_message_with_reply(): user tccd unavailable, sending 0x600000ab4000 to system tccd my_daemon [0x6000011b4000] activating connection: mach=true listener=false peer=false name=com.apple.tccd.system tccd [0x7fd4d1f7ed80] activating connection: mach=false listener=false peer=true name=com.apple.tccd.system.peer[76672].0x7fd4d1f7ed80 tccd REQUEST: tccd_uid=0, sender_pid=76672, sender_uid=0, sender_auid=-1, function=TCCAccessRequest, msgID=76672.1 tccd AUTHREQ_CTX: msgID=76672.1, function=<private>, service=kTCCServiceBluetoothAlways, preflight=no, query=1, client_dict=(null), daemon_dict=<private> tccd AUTHREQ_ATTRIBUTION: msgID=76672.1, attribution={requesting={TCCDProcess: identifier=my_daemon-5555494498236e3b5e2e395b93c13af176769937, pid=76672, auid=0, euid=0, binary_path=/Users/olivier/daemon/my_daemon}, }, tccd AUTHREQ_SUBJECT: msgID=76672.1, subject=/Users/olivier/daemon/my_daemon, tccd Refusing TCCAccessRequest for service kTCCServiceBluetoothAlways from client Sub:{/Users/olivier/daemon/my_daemon}Resp:{TCCDProcess: identifier=my_daemon-5555494498236e3b5e2e395b93c13af176769937, pid=76672, auid=0, euid=0, binary_path=/Users/olivier/daemon/my_daemon} in background session tccd AUTHREQ_RESULT: msgID=76672.1, authValue=0, authReason=5, authVersion=1, error=(null), tccd REPLY: (0) function=TCCAccessRequest, msgID=76672.1 my_daemon [0x6000011b4000] invalidated after the last release of the connection object bluetoothd Received XPC message "CBMsgIdTCCDone" from session "my_daemon-5555494498236e3b5e2e395b93c13af176769937-peripheral-76672-67" tccd [0x7fd4d1f7ed80] invalidated after getting a no-senders notification - client is gone bluetoothd [0x7f80482820f0] activating connection: mach=true listener=false peer=false name=com.apple.tccd.system tccd [0x7fd4d32585f0] activating connection: mach=false listener=false peer=true name=com.apple.tccd.system.peer[169].0x7fd4d32585f0 tccd REQUEST: tccd_uid=0, sender_pid=169, sender_uid=0, sender_auid=-1, function=TCCAccessRequest, msgID=169.48 tccd [0x7fd4d313d880] activating connection: mach=true listener=false peer=false name=com.apple.tccd tccd [0x7fd4d313d880] failed to do a bootstrap look-up: xpc_error=[3: No such process] bluetoothd [0x7f80482820f0] invalidated after the last release of the connection object bluetoothd Bluetooth user permission alwaysAuth: denied tccd [0x7fd4d313d880] invalidated after a failed init tccd FORWARD: to=com.apple.tccd/0, request: { require_purpose=<xpc_null> service="kTCCServiceBluetoothAlways" function="TCCAccessRequest" preflight=true target_token={pid:76672, auid:-1, euid:0} TCCD_MSG_ID="169.48" background_session=false } tccd REPLY: from=com.apple.tccd, reply: { XPCErrorDescription="Connection invalid" } tccd forwardMessage error: Connection invalid. tccd [0x7fd4d3152bf0] activating connection: mach=false listener=false peer=true name=com.apple.tccd.system.peer[169].0x7fd4d3152bf0 bluetoothd [0x7f80482820f0] activating connection: mach=true listener=false peer=false name=com.apple.tccd.system tccd REQUEST: tccd_uid=0, sender_pid=169, sender_uid=0, sender_auid=-1, function=TCCAccessRequest, msgID=169.49 tccd [0x7fd4d32585f0] invalidated after getting a no-senders notification - client is gone tccd [0x7fd4d1f4c810] activating connection: mach=true listener=false peer=false name=com.apple.tccd tccd [0x7fd4d1f4c810] failed to do a bootstrap look-up: xpc_error=[3: No such process] tccd [0x7fd4d1f4c810] invalidated after a failed init tccd FORWARD: to=com.apple.tccd/0, request: { require_purpose=<xpc_null> service="kTCCServiceBluetoothAlways" function="TCCAccessRequest" preflight=true target_token={pid:76672, auid:-1, euid:0} TCCD_MSG_ID="169.49" background_session=false } tccd REPLY: from=com.apple.tccd, reply: { XPCErrorDescription="Connection invalid" } tccd forwardMessage error: Connection invalid.

When I register & schedule a Background Task on an iPad, it runs properly. Running the exact same code on an M1 MacBook Pro, though, never schedules the task. There's no error, just a failure to schedule. After scheduling and calling getPendingTaskRequests, on the iPad you can see that it has a pending task, but not on the Mac. Why would this be? BGTaskScheduler.shared.register(forTaskWithIdentifier: taskIdentifier, using: nil) { [self] task in print("task to run") } do { try BGTaskScheduler.shared.submit(request) BGTaskScheduler.shared.getPendingTaskRequests { [self] tasks in print(tasks.count) //Prints 1 on iPad, prints 0 on Mac } } catch { //Code never comes here. print(error) }

Hi team, I'm working on an MQTT client for Apple platforms (macOS, iOS, and possibly tvOS and watchOS). I would like the client to listen to messages even when the application is in the background. I would appreciate any suggestions on the best approach to achieve this. Based on iOS Background Execution Limits, it seems that my best bet is to use a long-running background process with BGProcessingTaskRequest while setting up the connection. Does that sound like the right approach? Is there any limits for the bg tasks? I currently have a working BSD socket. I'm not sure if it is necessary to switch to the Network Framework to have the background task working, but I'm open to switching if it's necessary. If the approach works, does that mean I could built a http client to process large upload/download tasks without using NSURLSession? As I'm working on a cross platform project, it would be benefit if I dont need a separate http client implementation for Apple. Any insights on this topic would be greatly appreciated. Additionally, it's off topic, but the link to "WWDC 2020 Session 10063 Background Execution Demystified" (https://developer.apple.com/videos/play/wwdc2020/10063/) is broken. Is there a way to access the content there? Thanks in advance for your help and insights!

We have a BLE app and we are trying to get it to work in Background Mode consistently. Use case: RFID BLE reader is attached to a printer Person installs the iOS app on phone and enables Background Mode Person walks to the printer with phone iOS App connects to RFID BLE reader and authenticates to allow secure printing Current status/Problem: On several tests, we were able to connect to the BLE device, but with inconsistent results. For example, for 5 - 2 min tests - (1) we see 8 successful scans, (2) 1 successful scan, (3) 20 successful scans, (4) 15 successful scans, and (5) 11 successful scans. In the above tests, we were getting a scan every 3-4 secs and then it scanning stops. The objective is to maintain continuous scanning until user closes app or disables background mode. Why does scanning stop? How can we make scanning continuous? Any guidance you can provide is appreciated.

Hi, I'm developing a Live Activity Widget that shows a count down timer. In the current solution I have a stop watch that is responsible for handling the start, stop, resume, reset function. When the stop watch starts I have timer that calls on an updateTime function every 0.2 seconds. This works well. The problems comes when I try to use my stop watch in the Live Activity Widget. I have a timer that updates the live activity attributes with content every 0.5 second. // Start the activity let activity = try? Activity.request(... DispatchQueue.main.async { self.logger.log("Start internal timer") self.timer = Timer.scheduledTimer(withTimeInterval:0.5, repeats: true) { _ in self.logger.log("Update activity widget.") self.updateActivity() } } Is this a correct approach? If not what should I use to implement a stop watch with a count down timer and a corresponding progress bar/view?

My team and I would like to develop a mechanism that collects the user’s location a few times per day, to detect when the user travels to a different country, for the user’s convenience. The app is very likely going to be opened very rarely. The user would of course be made aware of why collecting the location a few times a day is desired - namely, saving them the effort of having to remember to open the app every time they travel. My question is the following: given that the app would rarely be interacted with, what is the best strategy for collecting the location? The goal is to handle scenarios where the OS might avoid sending location events or notifications to the app. I imagine that the backend might need to intervene and send the occasional push notification to remind the user to open the app from time to time. There are 3 strategies that I’m aware of: LocationManager’s startMonitoringSignificantLocationChanges Scheduling BGAppRefreshTasks Using silent push notifications scheduled by the server. Ideally, using a location push service extension Keeping in mind the “Background execution demystified” WWDC session, documentation, and other threads, I concluded the following: The first idea is probably the least suitable, since it probably requires the app to be opened often, and the location updates would not be sent by OS if the app has been terminated from the app switcher. The second approach would also suffer from infrequent use and termination. The third approach seems not to be affected as much by infrequent usage. I understand that the 3rd strategy might also lead to the OS omitting to wake up the app when it has been terminated by the user. How would you implement this mechanism?

Issue Statement: I am encountering difficulties with executing network calls from within a Flutter method during iOS native background task handling. Background: In my iOS Flutter application, I've implemented background task handling using native iOS code (Swift), leveraging the BGTaskScheduler's BGProcessingTask provided by iOS. The background task is set up to perform periodic network requests, but the network calls are made through a Flutter method invoked via platform channels from the iOS code. Problem Description: While the background task executes as expected and invokes the Flutter method successfully, the network calls initiated within the Flutter method fail to complete during background task execution. The method execution seems to proceed up to the point of initiating the network call, but the call itself does not complete successfully.