Health & Fitness

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Explore the technical aspects of health and fitness features, including sensor data acquisition, health data processing, and integration with the HealthKit framework.

Health & Fitness Documentation

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WorkoutKit WorkoutScheduler sync Broken with iOS 18.2 beta
WorkoutKit WorkoutScheduler seems broken with the first beta of iOS 18.2. I have tested using my app from Xcode and the one that is on the App Store (and working properly on other devices), and it's not working with this new beta of iOS. They appears in WorkoutScheduler.shared.scheduledWorkouts, but not on the watch. I even tried with other apps that do the same with Manual add to Apple Watch with SwiftUI workoutPreview work. Xcode 16.0 iOS 18.2 Beta 1 WatchOS 11.1
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WatchOS HealthKit HKObserverQuery crashes in background
I have a watchOS app with a connected iOS app using Swift and SwiftUI. The watchOS app should read heart rate date in the background using HKOberserQuery and enableBackgroundDelivery(), send the data to the iPhone app via WCSession. The iPhone app then sends the data to a Firebase project. The issue I am facing now it that the app with the HKObserverQuery works fine when the app is in the foreground, but when the app runs in the background, the observer query gets triggered for the first time (after one hour), but then always get terminated from the watchdog timeout with the following error message: CSLHandleBackgroundHealthKitQueryAction scene-create watchdog transgression: app<app.nanacare.nanacare.nanaCareHealthSync.watchkitapp((null))>:14451 exhausted real (wall clock) time allowance of 15.00 seconds I am using Xcode 16.3 on MacOS 15.4 The App is running on iOS 18.4 and watchOS 11.4 What is the reason for this this issue? I only do a simple SampleQuery to fetch the latest heart rate data inside the HKObserverQuery and then call the completionHandler. The query itself takes less than one second. Or is there a better approach to read continuously heart rate data from healthKit in the background on watchOS? I don't have an active workout session, and I don't need all heart rate data. Once every 15 minutes or so would be enough.
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HKObserverQuery stops delivering updates in background on watchOS 26
Hello, I’m building a health-related app for both watchOS and iOS, which needs to monitor certain health data (e.g., heart rate, active energy). Before updating to watchOS 26, the queries worked reliably without any issues. However, after adapting to watchOS 26, some users have reported that health data updates stop being delivered. What I’ve observed: HKObserverQuery with enableBackgroundDelivery is set up normally. On WatchOS 26, the query sometimes stops delivering updates entirely after a certain point, and once an update is missed, it may stop delivering further updates completely. Restarting the Apple Watch temporarily restores delivery, but the problem reoccurs after some time. This makes background health data monitoring unreliable for my app. Here’s a simplified version of the code we are using: guard let heartType = HKObjectType.quantityType(forIdentifier: .heartRate) else { return } let query = HKObserverQuery(sampleType: heartType, predicate: nil) { query, completionHandler, error in if let error = error { logEvent("Observer error: \(error.localizedDescription)") return } logEvent("Heart rate changed") MyNotificationManager.shared.sendNotification() // Send a local notification completionHandler() } healthStore.execute(query) healthStore.enableBackgroundDelivery(for: heartType, frequency: .hourly) { success, error in if success { logEvent("Background heart rate delivery enabled") } else { logEvent("Failed to enable background heart rate delivery: \(error?.localizedDescription ?? "Unknown error")") } } Could you please clarify: Is this a known issue with HKObserverQuery and enableBackgroundDelivery on watchOS 26? Are there any recommended workarounds or best practices to ensure continuous background delivery of health data? Thank you in advance for your help.
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watchOS 26.0.2 / iOS 26.0.1 + Workout Session Mirroring Failure
Hi, I have a workout app in the App Store which mirrors workout data between the phone and watch. Since iOS 26.x I've been having issues and received reports of the mirroring no longer working. Users in iOS 18 have no problems with this functionality. Bug description: A workout session is started from the phone app and starts mirroring to the watch companion device. The watch starts the workout session and then the mirroring session is disconnected / lost. Sending data to the companion device fails and ending the session on the phone doesn't end the session on the watch...essentially they become completely disconnected. Please note I am testing this on physical devices...not simulators. As a sanity check I've also tried the "Building a multidevice workout app" sample code and it has the same problem. To re-create on the sample app, I start a workout from the phone, the watch workout starts and then the mirroring session seems to disconnect and is unable to send data. This is the log from the "Building a multidevice workout app" sample code. Successfully started workout Type: Notice | Timestamp: 2025-10-17 06:57:07.341401+02:00 | Process: MirroringWorkoutsSample Watch App | Library: MirroringWorkoutsSample Watch App.debug.dylib | Subsystem: com.example.apple-samplecode.MirroringWorkoutsSampleABC123.watchkitapp | Category: MirroringWorkoutsSampleForWatch | TID: 0x1b2ca7 -[SPRemoteInterface _appRecoverAnyExtendedRuntimeSession:]_block_invoke:4350: Got no sessions back from -[CSLSSessionService existingRunningSessions:] or -[CSLSSessionService existingScheduledSessions:] after receiving a PUICInitializeSessionServiceAction Type: Error | Timestamp: 2025-10-17 06:57:07.641571+02:00 | Process: MirroringWorkoutsSample Watch App | Library: WatchKit | Subsystem: com.apple.watchkit | Category: default | TID: 0x1b2ca7 Session state changed from 1 to 2 Type: Notice | Timestamp: 2025-10-17 06:57:07.647883+02:00 | Process: MirroringWorkoutsSample Watch App | Library: MirroringWorkoutsSample Watch App.debug.dylib | Subsystem: com.example.apple-samplecode.MirroringWorkoutsSampleABC123.watchkitapp | Category: MirroringWorkoutsSampleForWatch | TID: 0x1b2e87 Failed to send data: Error Domain=com.apple.healthkit Code=100 "Failed to send data to remote session." UserInfo={NSLocalizedDescription=Failed to send data to remote session.} Type: Notice | Timestamp: 2025-10-17 06:57:07.669922+02:00 | Process: MirroringWorkoutsSample Watch App | Library: MirroringWorkoutsSample Watch App.debug.dylib | Subsystem: com.example.apple-samplecode.MirroringWorkoutsSampleABC123.watchkitapp | Category: MirroringWorkoutsSampleForWatch | TID: 0x1b2ca7 Would appreciate any help with this problem as it's affecting customers. Thank you
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Guidance / Documentation on iOS 18.6.1 Blood Oxygen Saturation
Are there any HealthKit related changes to be aware of in the new update that enables SPO2 / Blood Oxygen Saturation measurements on certain Apple Watch models within the US? I’m aware of processing happening on the phone…. But beyond that: Does this mean values are then saved to Apple Health? Do these models still take background SPO2 measurements in the same way as other models do? Are these values then visible in third party iOS apps as normal through HealthKit? Do these values sync back to the paired Apple Watch HealthKit store for third party apps to access on the Watch? For reference I have an iOS and WatchOS app that, amongst other features, provides the ability to see your SPO2 values in the Watch app, complications and in the iOS app.
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Sep ’25
Incorrect Step Count from Apple HealthKit Data
Hi, i'm trying to get the number of step counts a person has taken. I decided to pull the data from health kit and the number of steps are incorrect. Come to find out apple health recommends an app called pedometer++ for the number of steps counted and after testing I realized that they are getting the correct number of steps a person is taking. How can I pull the correct number of steps a person has taken? I want to be able to merge the data from watch and phone to make sure we are getting the correct number of steps but not double counting the steps either. any guidance on this would be appreciated! Here's the code snippet that i'm using right now: permissions: { read: [AppleHealthKit.Constants.Permissions.StepCount], write: [], }, }; AppleHealthKit.initHealthKit(permissions, error => { if (error) { console.log('Error initializing HealthKit: ', error); return; } else { dispatch(setAllowHealthKit(true)); getHealthKitData(); console.log('HealthKit initialized successfully'); } }); const getHealthKitData = async () => { try { const today = new Date(); const options = { startDate: new Date(today.setHours(0, 0, 0, 0)).toISOString(), endDate: new Date().toISOString(), }; const steps = await new Promise((resolve, reject) => { AppleHealthKit.getStepCount(options, (error, results) => { if (error) reject(error); resolve(results?.value); }); }); setStepsCount(steps); } catch (error) { console.error('Error fetching HealthKit data:', error); } };
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167
Jul ’25
Adding workoutEffortScore to HKWorkout
I'm trying to hook into the new workoutEffort score supported in iOS 18, I am collecting this information from users when they submit their workout and trying to add a sample to the HKWorkout in the same manner as I've been adding other samples like bodyweight, calories burned, etc. I'm receiving the error: HKWorkout: Sample of type HKQuantityTypeIdentifierWorkoutEffortScore must be related to a workout I tried adding the samples using HKWorkoutBuilder.add([samples]) as which has been working perfectly for calories burned & bodyweight, but I am receiving the above error for workoutEffortScore As a second approach, I tried adding the sample after I called finishWorkout on the HKWorkoutBuilder and received back the HKWorkout object using HKHealthStore.add([samples], to: HKWorkout) and am still receiving the same error! I don't know otherwise how to relate a sample to a workout, I thought those were the APIs to do so? I'm using Xcode 16.0 RC (16A242) and testing on an iOS 16 Pro simulator
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1.4k
Jul ’25
Workout mode drains battery heavily
I am building a watchOS app with iOS companion app. The watch app needs to track the heart rate during the night or while user is sleeping. And the desired frequency of measurement is 0.2Hz (every 5 seconds) For this I am using the HKWorkout mode with mindAndBody session. While it works fine, One of the main issue is: after about 6-7 hours of usage, the battery on the watch drains between 40% (Series 9) and 100% (series 7, I think) My questions: Are there any other option to track user's heart rate without workout, while the app could be in background? Another side effect of this workout mode is, Even if we choose not to save the workout in HealthKit, the Activity rings gets populated by this mindAndBody session, which makes it when the user is waking up, the bar is already full, This is not desired. Is there any option to specify for ActivityRing skips this? Highly appreciate any help in advance. Cheers - Prakash
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Dec ’24
Is sleep analysis data available in Smart Alarms?
I am working on a Smart Alarm app for Watch OS. When testing on an Series 10 watch, I am successfully able to read heart rate data in the ExtendedRuntimeSession. However, although the calls succeed, the sleep analysis data is all 0. The app successfully gets authorization for: [HKQuantityType(.heartRate), HKObjectType.categoryType(forIdentifier: .sleepAnalysis)!] I have read that sleep data is not available for less than an hour time period. The Smart Alarm extended session has a 30 minute limit. Does that mean it is not possible to read sleep analysis data in a Smart Alarm extended session? Thank you!
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901
Jan ’25
Healthstore read only in objective-C ?
I have an App in objective-c that is using Health data (walk/run, cycling) to give advice to users . I do not want/need to write any data in the Healtkit. If i do (with the 3 values in the plist / .info : self.healthStore requestAuthorizationToShareTypes:nil readTypes:readDataTypes My request crashes. *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Must request authorization for at least one data type' *** First throw call stack: ( 0 CoreFoundation 0x00000001804b910c __exceptionPreprocess + 172 1 libobjc.A.dylib 0x0000000180092da8 objc_exception_throw + 72 2 CoreFoundation 0x00000001804b901c -[NSException initWithCoder:] + 0 3 HealthKit 0x000000019da034d4 -[HKHealthStore _validateAuthorizationRequestWithShareTypes:readTypes:] + 92 4 HealthKit 0x000000019da03670 -[HKHealthStore requestAuthorizationToShareTypes:readTypes:shouldPrompt:completion:] + 292 BUT in swift : healthStore.requestAuthorization(toShare: nil, read: readTypes) is working, présents only my 2 datas to read... in the same IOS , same phone without crashing. What is the difference ? Nil object in objective-c and Nil object in swift are not the same ? how do i make readonly requests in objective C ?
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376
Mar ’25
Sleep Samples sum off by 2 minutes
Hi everyone! I'm trying to get the total sleep time for a given day, but users report that there's a difference between what my app reports and what the Apple Health app reports. In particular, we're off by 2 minutes less on average. What we're doing is: Get all the samples that are either core, deep, rem or unspecified Cut-off time at 3 PM previous day Merge overlapping intervals Add all the remaining intervals For debugging purposes I'm storing and sending all the raw samples to a server, and I have run tests and I don't find anything wrong. It looks like the number we come up with is correct according to our own rules. I wonder, how is Apple adding up all the samples to arrive at a number that's slightly off to our number. Any insight would be appreciated. Thanks.
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180
Mar ’25
Fitness app not now show saved routes
When I set the distanceFilter = 5 (5 meters) in the GPS CLLocationManager I can't display the workout routes in the Apple Fitness app after writing the recorded GPS data to HealthKit via HKWorkoutRouteBuilder. The smaller distanceFilter, Fitness will displays the route. Should I consider setting up a small distanceFilter when developing a workout app on watchOS?
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Jul ’25
HealthKit returns different values depending on the OS the request is made on
Hi, I've had trouble for a while now with HealthKit giving me different values if I make the request on iOS and WatchOS. I am using the exact same method on both with the same parameters but I get vast differences in the results. The code I am using to call HealthKit on both devices is: let dateRange = HKQuery.predicateForSamples(withStart: Date().removeMonths(numberOfMonths: 1), end: Date().endOfDay()) let predicate: NSPredicate predicate = NSCompoundPredicate(type: .and, subpredicates: [dateRange]) let query = HKStatisticsQuery(quantityType: HKQuantityType(.stepCount), quantitySamplePredicate: predicate, options: .cumulativeSum) { _, result, error in if error != nil { //print("Error fetching step count, or there is no data: \(error.localizedDescription), \(startDate) -> \(endDate)") onComplete(0) return } if let result, let sum = result.sumQuantity() { let stepCount = sum.doubleValue(for: HKUnit.count()) DispatchQueue.main.async { onComplete(Int(stepCount)) } } } healthStore.execute(query) }
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1.1k
Jun ’25
Integrating Apple Fitness+ Workouts – How to Retrieve Metadata?
Platform & Version: iOS Version: 18.3.1 Development Environment: Xcode 16.2, macOS 14.6.1 Description of the Issue: We're exploring ways to better integrate Apple Fitness+ workouts into our app. We've noticed that some third-party apps, such as Strava and HealthFit, now display Fitness+ workout details, including the title, trainer, and an image. I’ve been investigating how this is possible, and the only relevant change I’ve found is that HKMetadataKeyAppleFitnessPlusCatalogIdentifier is now being set for Fitness+ workouts. However, I can’t find any public API or official documentation that explains how to use these identifiers to retrieve the associated workout details. Question: Is there an official API available to fetch metadata for Fitness+ workouts using these identifiers? Or are these third-party apps potentially accessing private APIs? If no API exists, is the only option to create a manual mapping of these identifiers—something that seems impractical given the constantly evolving Fitness+ workout catalog? Any guidance on this would be greatly appreciated. Thanks!
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Feb ’25
How to get the same swimming distance like in the Fitness app
Hello Apple Community, What does approach use the Fitness app for swimming distance calculation per set (segment)? I've tried 2 options but all of them have different values than in the Fitness app. Calculation like that: pool length * number of laps = swimming distance BUT the Fitness app sometimes shows other values for distance per set (segment). Fetch all distance values via HKQuantityTypeIdentifier.distanceSwimming (HKSampleQuery`) and than try to match distance values with set (segment) duration. Again I got other values for swimming distance per set, values are bigger than in the Fitness app. let healthStore = HKHealthStore() let distanceType = HKQuantityType.quantityType(forIdentifier: HKQuantityTypeIdentifier.distanceSwimming)! let predicate = HKQuery.predicateForSamples(withStart: startDate as Date, end: endDate as Date?, options: .strictStartDate) let query = HKSampleQuery(sampleType: distanceType, predicate: predicate, limit: HKObjectQueryNoLimit, sortDescriptors: [.init(keyPath: \HKSample.startDate, ascending: true)], resultsHandler: { (query, results, error) in if let error { Logger.e("\(error)") continuation.resume(returning: nil) } continuation.resume(returning: results) }) healthStore.execute(query) Is it possible to get the same swimming distance like in the Fitness app per set via HealthKit?
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Mar ’25
HKObserverQuery not working in background
I'm developing a single target watchOS app that obtains HealthKit information. I have the "Background Delivery" option checked under "Signing &amp; Capabilities" for the watch target. The app does HKObserverQueries in the foreground that work as I would expect. But when I click the Digital Crown to return to clock face, the HKObserverQuery activity stops. I'm using Xcode 15.4, on Mac 14.5 and a Apple Watch Series 4 running 10.5.
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762
Mar ’25
App's domain being blocked/rerouted by Apple
I have a strange situation and I'm not sure where else to post this. Our app's domain (or at least its API hostname in the domain) resolves to something different only inside of Apple's network. I was able to get an Apple employee to verify this by resolving the API hostname while on Apple's corporate network and it resolves to an IP that is in Apple's 17.0.0.0/8 network, but everywhere else resolves to the normal IPs. Our domain's DNS is provided by Cloudflare and they are not doing anything special for Apple's network. This is causing problems during App Review because the app is trying to reach our API to log in and instead is being routed to an IP in Apple's network, so it fails SSL validation and presents an error dialog. App Review is then claiming our app doesn't work and rejecting it. This is an app that has been in the App Store for over a decade and gone through countless app reviews. App Review was of no help resolving this and I don't know where else to turn. How can I find out why our domain is being rerouted inside of Apple and get this fixed?
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520
Feb ’25
HKHealthStore().execute(query) will block main thread
HKHealthStore().execute(query) run in main thread it cost 3.5s here is my code print("execute begin:(Date().timeIntervalSince1970)") HKHealthStore().execute(query) print("execute end:(Date().timeIntervalSince1970)") query.predicate like this (startDate >= CAST(0.000000, "NSDate") AND endDate < CAST(0.100000, "NSDate") AND startDate < CAST(0.100000, "NSDate")) OR (startDate >= CAST(60.000000, "NSDate") AND endDate < CAST(60.100000, "NSDate") AND startDate < CAST(60.100000, "NSDate")) OR (startDate >= CAST(120.000000, "NSDate") AND endDate < CAST(120.100000, "NSDate") AND startDate < CAST(120.100000, "NSDate")) OR (startDate >= CAST(180.000000, "NSDate") AND endDate < CAST(180.100000, "NSDate") AND startDate < CAST(180.100000, "NSDate")) OR (startDate >= CAST(240.000000, "NSDate") AND endDate < CAST(240.100000, "NSDate") AND startDate < CAST(240.100000, "NSDate")) OR (startDate >= CAST(300.000000, "NSDate") AND endDate < CAST(300.100000, "NSDate") AND startDate < CAST(300.100000, "NSDate")) OR (startDate >= CAST(360.000000, "NSDate") AND endDate < CAST(360.100000, "NSDate") AND startDate < CAST(360.100000, "NSDate")) OR (startDate >= CAST(420.000000, "NSDate") AND endDate < CAST(420.100000, "NSDate") AND startDate < CAST(420.100000, "NSDate")) OR (startDate >= CAST(480.000000, "NSDate") AND endDate < CAST(480.100000, "NSDate") AND startDate < CAST(480.100000, "NSDate")) OR (startDate >= CAST(540.000000, "NSDate") AND endDate < CAST(540.100000, "NSDate") AND startDate < CAST(540.100000, "NSDate")) OR (startDate >= CAST(600.000000, "NSDate") AND endDate < CAST(600.100000, "NSDate") AND startDate < CAST(600.100000, "NSDate")) OR (startDate >= CAST(660.000000, "NSDate") AND endDate < CAST(660.100000, "NSDate") AND startDate < CAST(660.100000, "NSDate")) OR (startDate >= CAST(720.000000, "NSDate") AND endDate < CAST(720.100000, "NSDate") AND startDate < CAST(720.100000, "NSDate")) OR (startDate >= CAST(780.000000, "NSDate") AND endDate < CAST(780.100000, "NSDate") AND startDate < CAST(780.100000, "NSDate")) OR (startDate >= CAST(840.000000, "NSDate") AND endDate < CAST(840.100000, "NSDate") AND startDate < CAST(840.100000, "NSDate")) OR (startDate >= CAST(900.000000, "NSDate") AND endDate < CAST(900.100000, "NSDate") AND startDate < CAST(900.100000, "NSDate")) OR (startDate >= CAST(960.000000, "NSDate") AND endDate < CAST(960.100000, "NSDate") AND startDate < CAST(960.100000, "NSDate")) OR (startDate >= CAST(1020.000000, "NSDate") AND endDate < CAST(1020.100000, "NSDate") AND startDate < CAST(1020.100000, "NSDate")) OR (startDate >= CAST(1080.000000, "NSDate") AND endDate < CAST(1080.100000, "NSDate") AND startDate < CAST(1080.100000, "NSDate")) OR (startDate >= CAST(1140.000000, "NSDate") AND endDate < CAST(1140.100000, "NSDate") AND startDate < CAST(1140.100000, "NSDate")) OR (startDate >= CAST(1200.000000, "NSDate") AND endDate < CAST(1200.100000, "NSDate") AND startDate < CAST(1200.100000, "NSDate")) OR (startDate >= CAST(1260.000000, "NSDate") AND endDate < CAST(1260.100000, "NSDate") AND startDate < CAST(1260.100000, "NSDate")) OR (startDate >= CAST(1320.000000, "NSDate") AND endDate < CAST(1320.100000, "NSDate") AND startDate < CAST(1320.100000, "NSDate")) OR (startDate >= CAST(1380.000000, "NSDate") AND endDate < CAST(1380.100000, "NSDate") AND startDate < CAST(1380.100000, "NSDate")) OR (startDate >= CAST(1440.000000, "NSDate") AND endDate < CAST(1440.100000, "NSDate") AND startDate < CAST(1440.100000, "NSDate")) OR (startDate >= CAST(1500.000000, "NSDate") AND endDate < CAST(1500.100000, "NSDate") AND startDate < CAST( Log execute begin:1739958803.531026 execute end:1739958807.0448961
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Feb ’25