Background Tasks

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Request the system to launch your app in the background to run tasks using Background Tasks.

Posts under Background Tasks tag

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Maintaining MQTT connection in background
Hello, I have an app that receives critical alarms. This is usually done through remote push notifications from the server, but to add redundancy I'd like to add a MQTT connection as well. There are scenarios where internet connection might be missing (but there is a local WiFi connection to the server) hence I'd like to deliver the alarms directly from server to client without going out via the Internet. The problem is that according to all restrictions on iOS, the MQTT connection will not be maintained in the background and disconnect occurs within 20-30 sec after going in the background and shutting the screen. I'm aware of all the background modes that iOS allows but none fall within this scenario. Is there a way to maintain a MQTT connection (or some other type of network connection) in the background on iOS?
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425
Apr ’24
AudioSession activation while App is in background or killed
Hello, I'm developing a voice communication App using Livekit SDK. Everything works fine in the foreground, AudioSession is activated and audio transmitted. However, I would like to add a feature, I would like my app to receive audio even when it's in background or terminated. I know I can run code when the App is in that state by sending a background push notification, but the only thing that is not working in that case is the AudioSession activation. It fails with error "Session activation failed", no more clues. I tried every combination of category and mode, but no success. Bacground modes in XCode have been activated: -Audio, AirPlay, and Picture in Picture -Background Processing Is this a limit of Livekit? I would be grateful if someone can point me into the right direction.
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382
Apr ’24
BGTask running while iPad is awake--how is this possible?
We have been using the BGTask (specifically a BGProcessingTask) reliably for the last couple of years for our app. Up until now they wake up automatically while the screen is off, the iPad is plugged in, and the app is running (that is, in the background), but never while the screen is on (that is, never when the scenePhase == .active). For the last month or so, I've noticed that they are triggering now while the screen is displayed. How is this possible??? Did something change with a recent version of iOS? It's violating Apple's own documentation, which describes the BGProcessingTask as: "A time-consuming processing task that runs while the app is in the background."
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424
Mar ’24
How to run a background task on keyboard extension to communicate with a MFi device?
I'm working on a app that can communicate, send and receive data from our own MFi scanner. Ideally, this app can receives data and remains communication even when it's in background, but I can only runs a background task for maximum 30 sec. Along with this main app, we also have a keyboard extension as an interface that can publish collected data to other app that user prefers with string format. However, It seems like Apple doesn't allow to implement UIApplication.shared.beginBackgroundTask method in extension class, is there any alternative that worth to try? Also, can I extend app background task time elapsed to at least 30 minutes? If I can get an official response would be great!
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506
Mar ’24
Error: _SwiftData_SwiftUI: one-time initialization function for empty
My App keeps crashing in the background and I don't know why. I'm using SwiftData and SwiftUI. I'm setting up a .backgroundTask like this: import SwiftUI import SwiftData import TipKit @main struct MyAppName: App { @UIApplicationDelegateAdaptor(AppDelegate.self) var appDelegate @State var navManager = NavigationManager.load() @State var alerter: Alerter = Alerter() var sharedModelContainer: ModelContainer = { do { return try ModelContainer(for: DataController.schema, configurations: [DataController.modelConfig]) } catch { fatalError("Could not create ModelContainer: \(error)") } }() var body: some Scene { WindowGroup { SetupView() .accentColor(.myAccentColor) .environment(alerter) .alert(isPresented: $alerter.isShowingAlert) { alerter.alert ?? Alert(title: Text(verbatim: "")) } .task { try? Tips.configure([ .displayFrequency(.immediate), .datastoreLocation(.applicationDefault) ]) } .onAppear { setUpAppDelegate() } } .modelContainer(sharedModelContainer) .backgroundTask(.appRefresh(Const.backgroundAppRefreshId)) { @MainActor in let container = sharedModelContainer await RefreshManager.handleBackgroundVideoRefresh(container) } .environment(navManager) } func setUpAppDelegate() { appDelegate.navManager = navManager } } The RefreshManager.handleBackgroundRefresh(...) goes on to load data and then insert models for them via SwiftData. It only happens occasionally and afaik only in the background. Weirdly enough the issue seems to be there even when I only print something in the background task. Even when I don't schedule/set a background task at all. How can that be? The crashes started in the version that included the .backgroundTask, although perhaps it's related to something else. I'm still trying to further narrow it down. This is the crash report that I'm getting: Exception Type: EXC_BREAKPOINT (SIGTRAP) Exception Codes: 0x0000000000000001, 0x00000001a1bb98c0 Termination Reason: SIGNAL 5 Trace/BPT trap: 5 Terminating Process: exc handler [809] Triggered by Thread: 0 Thread 0 name: Thread 0 Crashed: 0 libswiftCore.dylib 0x00000001a1bb98c0 _assertionFailure(_:_:file:line:flags:) + 264 (AssertCommon.swift:144) 1 libswiftCore.dylib 0x00000001a1c27d14 swift_unexpectedError + 664 (ErrorType.swift:188) 2 _SwiftData_SwiftUI 0x000000024310cd78 one-time initialization function for empty + 300 (ModelContainer+Extensions.swift:5) 3 libdispatch.dylib 0x00000001ab16add4 _dispatch_client_callout + 20 (object.m:576) 4 libdispatch.dylib 0x00000001ab16c654 _dispatch_once_callout + 32 (once.c:52) 5 _SwiftData_SwiftUI 0x000000024310cdf8 one-time initialization function for empty + 124 (ModelContainer+Extensions.swift:12) 6 libdispatch.dylib 0x00000001ab16add4 _dispatch_client_callout + 20 (object.m:576) 7 libdispatch.dylib 0x00000001ab16c654 _dispatch_once_callout + 32 (once.c:52) 8 _SwiftData_SwiftUI 0x0000000243122170 key path getter for EnvironmentValues.modelContext : EnvironmentValues + 140 (<compiler-generated>:0) 9 libswiftCore.dylib 0x00000001a1ce4628 RawKeyPathComponent._projectReadOnly<A, B, C>(_:to:endingWith:) + 1012 (KeyPath.swift:1701) 10 libswiftCore.dylib 0x00000001a1ce3ddc KeyPath._projectReadOnly(from:) + 1036 (KeyPath.swift:331) 11 libswiftCore.dylib 0x00000001a1ce8348 swift_getAtKeyPath + 24 (KeyPath.swift:2029) 12 SwiftUI 0x00000001a7af4814 EnvironmentBox.update(property:phase:) + 872 (Environment.swift:273) 13 SwiftUI 0x00000001a782a074 static BoxVTable.update(ptr:property:phase:) + 396 (DynamicPropertyBuffer.swift:294) 14 SwiftUI 0x00000001a78297b0 _DynamicPropertyBuffer.update(container:phase:) + 104 (DynamicPropertyBuffer.swift:215) 15 SwiftUI 0x00000001a887fb78 closure #1 in closure #1 in DynamicBody.updateValue() + 104 (DynamicProperty.swift:447) 16 SwiftUI 0x00000001a887fbb8 partial apply for closure #1 in closure #1 in DynamicBody.updateValue() + 28 (<compiler-generated>:0) 17 libswiftCore.dylib 0x00000001a1bcc068 withUnsafeMutablePointer<A, B>(to:_:) + 28 (LifetimeManager.swift:82) 18 SwiftUI 0x00000001a887f9dc closure #1 in DynamicBody.updateValue() + 408 (DynamicProperty.swift:446) 19 SwiftUI 0x00000001a887f5c0 DynamicBody.updateValue() + 712 (DynamicProperty.swift:445) 20 SwiftUI 0x00000001a71e8bf8 partial apply for implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 32 (<compiler-generated>:0) 21 AttributeGraph 0x00000001cbd4c240 AG::Graph::UpdateStack::update() + 512 (ag-graph-update.cc:578) 22 AttributeGraph 0x00000001cbd42f38 AG::Graph::update_attribute(AG::data::ptr<AG::Node>, unsigned int) + 424 (ag-graph-update.cc:719) 23 AttributeGraph 0x00000001cbd42810 AG::Graph::input_value_ref_slow(AG::data::ptr<AG::Node>, AG::AttributeID, unsigned int, unsigned int, AGSwiftMetadata const*, unsigned char&, long) + 720 (ag-graph.cc:1429) 24 AttributeGraph 0x00000001cbd423a4 AGGraphGetValue + 228 (AGGraph.mm:701) 25 SwiftUI 0x00000001a887f548 DynamicBody.updateValue() + 592 (DynamicProperty.swift:444) 26 SwiftUI 0x00000001a71e8bf8 partial apply for implicit closure #1 in closure #1 in closure #1 in Attribute.init<A>(_:) + 32 (<compiler-generated>:0) 27 AttributeGraph 0x00000001cbd4c240 AG::Graph::UpdateStack::update() + 512 (ag-graph-update.cc:578) 28 AttributeGraph 0x00000001cbd42f38 AG::Graph::update_attribute(AG::data::ptr<AG::Node>, unsigned int) + 424 (ag-graph-update.cc:719) [...] 107 SwiftUI 0x00000001a7cf79fc static App.main() + 132 (App.swift:114) 108 MyAppName 0x0000000100e6d120 static MyAppNameApp.$main() + 52 (MyAppNameApp.swift:0) 109 MyAppName 0x0000000100e6d120 main + 64 110 dyld 0x00000001c67c2d84 start + 2240 (dyldMain.cpp:1298) The report also says key path getter for EnvironmentValues.modelContext, which seems odd. Any idea where I could start to look for the issue? I'm currently just trying things out, pushing them to TestFlight and waiting for crashes to happen. As soon as I can narrow it down further I'll update this.
6
1
729
Apr ’24
Cannot start a new Extended Runtime Session on watchOS
XCode 15.3, watchOS 10.4 SDK Our health-related app is exploring adding an additional feature that would make use of extended runtime sessions to guide users through an activity. A user starts a session by tapping a button on the watchOS app's interface. If a session is already running, pressing that button should cause the current session to invalidate, and a new session should be created so we can start again from the beginning. TLDR: Running new sessions works as expected on the simulator but not on a real device. Why? We currently have a barebones implementation that includes logging in the extended runtime session delegate functions, on the button push, and when the new session is about to start. Here's what our logging output for the simulator looks like when we try to invalidate the current session and run another one: Invalidating extended session Optional("<WKExtendedRuntimeSession: 0x60000262d7a0> state=2, sessionID=4894EB1D-96F7-4921-8263-378E304E719F, expirationDate=2024-03-20 13:01:10 +0000") at 12:01:21 PM Extended runtime session <WKExtendedRuntimeSession: 0x60000262d7a0> state=3, sessionID=4894EB1D-96F7-4921-8263-378E304E719F, expirationDate=2024-03-20 13:01:10 +0000 invalidated for reason WKExtendedRuntimeSessionInvalidationReason(rawValue: 0) with error nil at 12:01:21 PM Requesting new extended session in application state 0 at 12:01:22 PM Starting new extended session Optional("<WKExtendedRuntimeSession: 0x600002644540> state=0, sessionID=B34ECCFF-A0DA-45C1-9FD1-FD0F335FBE02, expirationDate=(null)") in application state 0 at 12:01:23 PM Did start extended session <WKExtendedRuntimeSession: 0x600002644540> state=2, sessionID=B34ECCFF-A0DA-45C1-9FD1-FD0F335FBE02, expirationDate=2024-03-20 13:01:23 +0000 at 12:01:23 PM As you can see, we successfully invalidate a running session, a button press requests a new one, and then we create and start a new runtime session instance which ends in the running (2) state. We can repeat this over and over without issue. The exact same code running on an actual device produces this: Invalidating extended session Optional(\"<WKExtendedRuntimeSession: 0x15db5750> state=2, sessionID=889FE2E8-0FDA-4826-9094-4D48094FEBED, expirationDate=2024-03-20 12:53:55 +0000\") at 11:56:04AM Extended runtime session <WKExtendedRuntimeSession: 0x15db5750> state=3, sessionID=889FE2E8-0FDA-4826-9094-4D48094FEBED, expirationDate=2024-03-20 12:53:55 +0000 invalidated for reason WKExtendedRuntimeSessionInvalidationReason(rawValue: 0) with error nil at 11:56:04AM Requesting new extended session in application state 0 at 11:56:05AM Starting new extended session Optional(\"<WKExtendedRuntimeSession: 0x15e0aba0> state=0, sessionID=D5020337-D20B-48BE-B2EE-EE44BE580AEC, expirationDate=(null)\") in application state 0 at 11:56:06AM Extended runtime session <WKExtendedRuntimeSession: 0x15e0aba0> state=3, sessionID=D5020337-D20B-48BE-B2EE-EE44BE580AEC, expirationDate=(null) invalidated for reason WKExtendedRuntimeSessionInvalidationReason(rawValue: 1) with error nil at 11:56:06AM The difference is in the last line: starting the session was unsuccessful and it was immediately invalidated, with the reason WKExtendedRuntimeSessionInvalidationReason(rawValue: 1) which maps to the enum sessionInProgress. This is surprising, since we just invalidated and dereferenced the old runtime session. What else can we do to tear down this session? In fact, no other extended runtime sessions can be created and started successfully until the device is rebooted. One note is that on the simulator we do get the following warning right after invalidating the running session: -[WKExtendedRuntimeSession _invalidateWithError:]_block_invoke_2:527: Got error Error Domain=com.apple.CarouselServices.SessionErrorDomain Code=3 "Session not running <CSLSession: 0x600003b4eca0; pid: 8833; dismissed: NO; ended: YES; duration: 3600.0; autoEnd: NO; launchable: NO; mutuallyExclusive: YES; managed: YES; persisted: NO; requiresFGActiveInitiation: YES; lastForeground: 2024-03-20 12:01:21 +0000> |CSLSSession = { | sessionID: 4894EB1D-96F7-4921-8263-378E304E719F; bundleID: com.bundle; type: "physical therapy"; running: NO; paused: NO; expirationDate: 2024-03-20 13:01:10 +0000; supportsAOT: NO; lastStartWasScheduled: NO; remote: NO; |}" UserInfo={NSLocalizedDescription=Session not running <CSLSession: 0x600003b4eca0; pid: 8833; dismissed: NO; ended: YES; duration: 3600.0; autoEnd: NO; launchable: NO; mutuallyExclusive: YES; managed: YES; persisted: NO; requiresFGActiveInitiation: YES; lastForeground: 2024-03-20 12:01:21 +0000> |CSLSSession = { | sessionID: 4894EB1D-96F7-4921-8263-378E304E719F; bundleID: com.bundle; type: "physical therapy"; running: NO; paused: NO; expirationDate: 2024-03-20 13:01:10 +0000; supportsAOT: NO; lastStartWasScheduled: NO; remote: NO; |}} This appears to be thrown by some part of Carousel, for which no public documentation exists, and it clearly doesn't disrupt the expected behavior on the simulator. I don't know if this is being thrown on the device, since our logging wouldn't be able to pick it up. Please let me know if we are approaching this incorrectly or if there are any known solutions to this issue.
4
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580
Apr ’24
Live Activity Stops Updating after iPhone Lock
My background audio app stops updating its Live Activity after the iPhone locks, and doesn't resume updating the activity after tapping the screen or even after FaceID unlocks the device (without opening the lock screen). My live activity requests a ContentState update & iOS updates the content for the activity as below: Task{ log.debug("LiveActivityManager.updateLiveActivity() with new ContentState") await liveActivity.update( ActivityContent(state:contentState, staleDate:nil) ) } Below what my log looks like: <<<<SWIPE LOCK SCREEN DOWN>>>> DEBUG: LiveActivityManager.updateLiveActivity() with new ContentState iOS: Updating content for activity 0A519263-1E46-4BB6-BA4F-F3DDBC081AB4 DEBUG: LiveActivityManager.updateLiveActivity() with new ContentState iOS: Updating content for activity 0A519263-1E46-4BB6-BA4F-F3DDBC081AB4 <<<<PRESS LOCK BUTTON->Lock iPhone>>>> INFO: --------protectedDataWillBecomeUnavailableNotification-------- DEBUG: LiveActivityManager.updateLiveActivity() with new ContentState iOS: Updating content for activity 0A519263-1E46-4BB6-BA4F-F3DDBC081AB4 DEBUG: LiveActivityManager.updateLiveActivity() with new ContentState DEBUG: LiveActivityManager.updateLiveActivity() with new ContentState DEBUG: LiveActivityManager.updateLiveActivity() with new ContentState <<<<LOOK AT & TAP LOCK SCREEN->Unlock iPhone without swiping up>>>> INFO: --------protectedDataDidBecomeAvailableNotification----------- DEBUG: LiveActivityManager.updateLiveActivity() with new ContentState DEBUG: LiveActivityManager.updateLiveActivity() with new ContentState DEBUG: LiveActivityManager.updateLiveActivity() with new ContentState As shown in the log, normally iOS updates the content for my activity after my liveActivity.update request. This works fine in the Dynamic Island and when after switching apps and swiping down to see the lock screen without locking the phone. However, once I lock the phone, iOS stops updating the Live Activity content, and doesn't resume updates until after the app regains the foreground at least once. Has anyone else encountered this behavior? Is this a setting that I'm missing, or a bug?
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932
1w
My background task needs more time
I'm working on a screen where the goal is for the user to walk for 6 minutes while the app times them and measures the distance walked. I'm using CMPedometer to track the walking distance and a repeating 1-second Timer to count down the time. This works fine as long as the app is in the foreground, but I'd like my user to be able to lock their phone and put it away while they walk. I used UIApplication.shared.beginBackgroundTask, but it doesn't provide enough time. It usually only gives me around 30 seconds. I also tried calling UIApplication.shared.beginBackgroundTask again or calling it once every time the timer ticks, with no better result. How can I accomplish my goal here?
1
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489
Mar ’24
iOS app acting as MJPEG client in the background
We are developing a SwiftUI iOS app which behaves as a client to a MJPEG server on a local network. This means that our app should read images sent from a special hardware we are developing using HTTP protocol. The testing is working fine, but our concern is that when the app goes to the background or the phone is locked, the HTTP connection gets closed after one minute. However, we need to have this HTTP connection alive all the time because we are developing a safety monitoring app that should continue its monitoring state even when the phone is locked. We are constantly running object detection AI algorithm on the transferred images from the hardware. Is there a solution to our concern. Could we have example code to a solution?
2
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432
Feb ’24
Use external camera in background iOS app
Is there a possibility to develop an iOS app that is connected to an external camera connected through lightning or USB-C port and receives video stream. We need to be able to get this video stream even while the app is in the background or if the phone is locked. We could have the camera connected wirelessly through the lightning port. Is there an available library or a sample app featuring such functionalities. Thanks.
1
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466
Feb ’24
Cocoa Pods App not working in BGAppRefreshTask
I have an app which uses Cocoa Pods to use MQTTClient in connecting to io.adafruit. I use the app to get the various data point stored at io.adafruit and to even send data to adafruit to control a connected unit. I am using .xcworkspace to upload the app on my phone and everything works fine. I am hoping to wake my app every so ofter to get some data points from io.adafruit and if certain conditions exist, I want to send a notification to the user. I have added Background Modes to my app's Signing & Capabilities (Background fetch) and in my INFO I have Permitted background task scheduler identifiers with the String identifier LEVELIT.Refresh. The following is my code I am using in my AppDelegate.h #import <UIKit/UIKit.h> #import <CoreData/CoreData.h> #import <MQTTClient/MQTTClient.h> #import <UserNotifications/UserNotifications.h> @interface AppDelegate: UIResponder <UIApplicationDelegate, UNUserNotificationCenterDelegate,UIAlertViewDelegate,MQTTSessionDelegate>{ MQTTSession *session3; } @property (nonatomic, retain) MQTTSession *session3; @property (nonatomic, strong) NSPersistentContainer *persistentContainer; @end And this is the code I use in my AppDelegate.m #import "AppDelegate.h" #import <BackgroundTasks/BackgroundTasks.h> #import <CloudKit/CloudKit.h> #import <UserNotifications/UserNotifications.h> static NSString* TaskID = @"LEVELIT.refresh"; @interface AppDelegate() @property (nonatomic, retain) NSString *myUserName; @property (nonatomic, retain) NSString *myUserKey; @property (nonatomic, retain) NSString *myTrips; @property (nonatomic, retain) NSString *atrip; @property (nonatomic, retain) NSString *trip; @property (nonatomic, retain) NSString *gettrip; @property(strong) void (^expirationHandler)(void); @end @implementation AppDelegate @synthesize session3,window; - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { if (@available(iOS 13.0, *)) { [[BGTaskScheduler sharedScheduler] registerForTaskWithIdentifier:TaskID usingQueue:nil launchHandler:^(BGAppRefreshTask *task) { [self handleAppRefreshTask:task]; }]; } else { // Fallback on earlier versions } UNUserNotificationCenter* center = [UNUserNotificationCenter currentNotificationCenter]; [center requestAuthorizationWithOptions:(UNAuthorizationOptionAlert + UNAuthorizationOptionSound) completionHandler:^(BOOL granted, NSError * _Nullable error) { }]; UNNotificationCategory* generalCategory = [UNNotificationCategory categoryWithIdentifier:@"GENERAL" actions:@[] intentIdentifiers:@[] options:UNNotificationCategoryOptionCustomDismissAction]; NSUserDefaults *defaults2 = [NSUserDefaults standardUserDefaults]; if([[[defaults2 dictionaryRepresentation] allKeys] containsObject:@"myUserNameFile"]){ NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults]; self.myUserName = [defaults objectForKey:@"myUserNameFile"]; NSLog(@"myUserName1:%@",self.myUserName); self.myUserKey = [defaults objectForKey:@"myUserKeyFile"]; NSLog(@"myUserKey1:%@",self.myUserKey); } return YES; } } -(void)schedualLocalNotifications{ } - (void)setTaskCompletedWithSuccess:(BOOL)success;{ NSLog(@"Completed"); } - (void)applicationDidEnterBackground:(UIApplication *)application { NSLog(@"Entering background"); if (@available(iOS 13.0, *)) { BGAppRefreshTaskRequest *request = [[BGAppRefreshTaskRequest alloc] initWithIdentifier:TaskID]; request.earliestBeginDate = [NSDate dateWithTimeIntervalSinceNow:15*60]; NSError *error; BOOL success = [[BGTaskScheduler sharedScheduler] submitTaskRequest:request error:&error]; if (success == TRUE) { } } //BREAKPOINT } -(void)handleAppRefreshTask:(BGAppRefreshTask *)task API_AVAILABLE(ios(13.0)){ //do things with task NSLog(@"Process started!"); task.expirationHandler = ^{ NSLog(@"WARNING: expired before finish was executed."); }; MQTTCFSocketTransport *transport = [[MQTTCFSocketTransport alloc] init]; transport.host = @"io.adafruit.com"; transport.port = 1883; self.session3 = [[MQTTSession alloc] init]; self.session3.userName = self.myUserName; self.session3.password = self.myUserKey; self.session3.transport = transport; self.session3.delegate = self; self.session3.keepAliveInterval = 30; // new stuff NSString *feeds = [self.myUserName stringByAppendingString:@"/feeds/"]; self.atrip = [feeds stringByAppendingString:@"trip"]; self.gettrip = [self.atrip stringByAppendingString:@"/get"]; [session3 connectWithConnectHandler:^(NSError *error) { if(!error){ [self.session3 subscribeToTopic:self.atrip atLevel:1 subscribeHandler:^(NSError *error, NSArray *gQoss){ if (error) { NSLog(@"Subscription failed %@", error.localizedDescription); } else { NSLog(@"Subscription sucessfull! Granted Qos: %@", gQoss); NSData* data = [@"0" dataUsingEncoding:NSUTF8StringEncoding]; [self.session3 publishData:data onTopic:self.gettrip retain:NO qos:0 publishHandler:nil]; } }]; dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(45* NSEC_PER_SEC)), dispatch_get_main_queue(), ^{ [task setTaskCompletedWithSuccess:YES]; }); self.session3.keepAliveInterval =30; } else {NSLog(@"[connectWithConnectHandler]Error Connect %@", error.localizedDescription);} }]; task.expirationHandler = ^{ NSLog(@"WARNING: expired before finish was executed."); }; } } } //More code here but too much. @end I am not sure about the local notification because the BGAppRefreshTask is not working. I have placed a breakpoint just after the app enters background and the TASK is submitted. Then I type in e -l objc -- (void)[[BGTaskScheduler sharedScheduler] _simulateLaunchForTaskWithIdentifier:@"LEVELIT.refresh"] The app launches in the background but I get an error error: Header search couldn't locate module MQTTClient error: couldn't install checkers, unknown error Message from debugger: Terminated due to signal 9 When I tried running the app without .xcworkspace the project said it couldn't find MQTTClient. But with the workspace everything works fine. Why would launching the app in the background cause the app not to locate the MQTTClient libraries? And how do I work around this problem? Any and all help would be appreciated.
7
0
478
Feb ’24
Running Bluetooth (BLE) tasks in background, with React Native
Currently working on an emergency app paired with a BLE device, and the desired use case is: When the device is triggered, it sends your location to your emergency contacts an API we've built. This flow works while the app is open, but we need things to obviously work while in background (while the phone is sleeping as well, of course, for emergency contexts) From what I've researched and understood, background fetches don't really work, because the intervals are a maximum of about 15 minutes, and iOS will make them less frequent based on app usage, and that window in an emergency situation isn't good enough. Having read around, I've bumped into a couple resources that suggest background bluetooth processing is possible, if I listen for a particular service being advertised, but I haven't been able to make things work so far. I wanted some help on this.
2
0
742
Feb ’24
Playing Timed Sound Effects in Background
Hi, I'm relatively new to iOS development and kindly ask for some feedback on a strategy to achieve this desired behavior in my app. My Question: What would be the best strategy for sound effect playback when an app is in the background with precise timing? Is this even possible? Context: I created a basic countdown timer app (targeting iOS 17 with Swift/SwiftUI.). Countdown sessions can last up to 30-60 mins. When the timer is started it progresses through a series of sub-intervals and plays a short sound for each one. I used AVAudioPlayer and everything works fine when the app is in the foreground. I'm considering switching to AVAudioEngine b/c precise timing is very important and the AIs tell me this would have better precision. I'm already setting "App plays audio or streams audio/video using AirPlay" in my Plist, and have configured: AVAudioSession.sharedInstance().setCategory(.playback, mode: .default, options: .mixWithOthers) Curiously, when testing on my iPhone 13 mini, sounds sometimes still play when the app is in the background, but not always. What I've considered: Background Tasks: Would they make any sense for this use-case? Seems like not if the allowed time is short &amp; limited by the system. Pre-scheduling all Sounds: Not sure this would even work and seems like a lot of memory would be needed (could be hundreds of intervals). ActivityKit Alerts: works but with a ~50ms delay which is too long for my purposes. Pre-Render all SFX to 1 large audio file: Seems like a lot of work and processing time and probably not worth it. I hope there's a better solution. I'd really appreciate any feedback.
0
0
582
Feb ’24
L2CAP channel doesn't work in background
I have an app to communicate with a peripheral via L2CAP channel. Even I already enabled "Uses Bluetooth LE accessories" in "Background Mode", it still stop working when I lock the screen. Did some search and found these two posts: CBL2CAPChannel not responsive while app is backgrounded iOS Swift CoreBluetooth CBL2CAPChannel L2CAP Channel Oriented Connection Cannot Reconnect After Close From Central I am wondering if there are any solutions or work around about this. Based on the use case, I prefer to use L2CAP to transfer large data between two devices, so won't consider GATT.
1
0
495
Feb ’24
handleBackgroundTasks not called on apple watch but only on simulator
I'm trying to execute a background task following the Developer Documentation. This is my code import SwiftUI @main struct MyAppTest_Watch_AppApp: App { @Environment(\.scenePhase) var scenePhase let bs = BackgroundSession() @SceneBuilder var body: some Scene { WindowGroup { ContentView() }.backgroundTask(.appRefresh("prova")) { context in print("bg task") await scheduleTask() } .onChange(of: scenePhase) { phase in switch phase { case .active: print("\(#function) REPORTS - App change of scenePhase to ACTIVE") case .inactive: print("\(#function) REPORTS - App change of scenePhase Inactive") case .background: print("\(#function) REPORTS - App change of scenePhase Background") WKApplication.shared() .scheduleBackgroundRefresh( withPreferredDate: Date.init(timeIntervalSinceNow: 5 * 60.0), userInfo: "prova" as NSSecureCoding & NSObjectProtocol, scheduledCompletion: schedule) default: print("\(#function) REPORTS - App change of scenePhase Default") } } } func scheduleTask() async { bs.testSession() await WKApplication.shared() .scheduleBackgroundRefresh( withPreferredDate: Date.init(timeIntervalSinceNow: 5 * 60.0), userInfo: "prova" as NSSecureCoding & NSObjectProtocol, scheduledCompletion: schedule) } func schedule(error: Error?) { if error != nil { // Handle the scheduling error. fatalError("*** An error occurred while scheduling the background refresh task. ***") } print("Scheduled!") } } On the simulator the background refresh occurs correctly according to the preferred date and executes the background task, on the real watch it does not. I also set the app as complication in my watch face. The device I'm testing the app on is an Apple Watch Serie 7 with watchOS 10.3. Any idea?
0
0
382
Feb ’24
Monitoring for network changes while backgrounded or suspended
Detecting New WiFi Connection + WiFi Details What I want to accomplish: The app, including when backgrounded or suspended, creates a local notification (assuming the app has permission for notifications) when there is a new WiFi network being used and ideally being able to execute some small code to customize the notification. This code would also have access to SSID info, security type, etc., so the sort of info in NEHotspotNetwork. A number of apps seem able to do this but I am having trouble replicating what they are doing. What I’ve looked at or tried: Looking at “TN3111: iOS Wi-Fi API overview” https://developer.apple.com/documentation/technotes/tn3111-ios-wifi-api-overview Navigate an internet hotspot (NEHotspotHelper) Doesn’t look like NEHotspotHelper would provide the above functionality for detecting changes while backgrounded and it seems to indicate that the special entitlement com.apple.developer.networking.HotspotHelper would not be granted for this use case anyway. Add an accessory to the user’s network (Wireless Accessory Configuration (WAC) or HomeKit) Doesn’t seem relevant to my use case Peer-to-peer networking Doesn’t seem relevant to my use case Location tracking I don’t want to know my user’s location and Lookout and Norton 360 (just two of many examples) don’t request or have location permissions (or request any permissions for that matter except notifications) and are still able to obtain the WiFi network info without it as well as detect changes in the background. Current Wi-Fi network NEHotspotNetwork .fetchCurrent(completionHandler:) So this is the most obvious since it returns the info I want but it requires the following permissions or configurations that neither Lookout or Norton 360 are requesting and also I don’t see how this API would trigger a backgrounded app to run, more for when your app is in the foreground and able to run already. From Apple docs: “This method produces a non-nil NEHotspotNetwork object only when the current network environment meets all four of the following critieria: The app is using the Core Location API and has user’s authorization to access precise location. The app used the NEHotspotConfiguration API to configure the current Wi-Fi network. The app has active VPN configurations installed. The app has an active NEDNSSettingsManager configuration installed. This method also requires the app to have the Access Wi-Fi Information Entitlement, and produces nil if the app lacks this entitlement.” Once again, apps that are able to do what I want don't seem to have location permissions, no VPN profile, no DNS config, no hotspot config.... Additional things I’ve considered that are not mentioned in the above: Using NWPathMonitor works for identifying a change, doesn’t trigger when app backgrounded and no access to SSID or other WiFi info. What am I missing? Is there some API that I totally missed? Thank you! Colin
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Feb ’24