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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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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Sleep Analysis inBed sample not recorded on Apple Watch in iOS 18
In this link, Apple states we can know when a user is in bed vs sleeping and compare their quality of sleep by it. Only, in iOS 18, Apple no longer reports inBed time samples for the Apple Watch. I get why they stopped doing this for the phone, but why the watch? Bug? My app was using the inBed times for this very purpose and now only works for Garmin and Oura who still report inBed times. https://developer.apple.com/documentation/healthkit/hkcategoryvaluesleepanalysis
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Dec ’24
healthStore.workoutSessionMirroringStartHandler never called
I'm trying to run this example project: https://developer.apple.com/documentation/HealthKit/building-a-multidevice-workout-app When I run it on my device (iPhone 16 Pro and Apple Watch Ultra 2) I get this error: -[SPRemoteInterface _appRecoverAnyExtendedRuntimeSession:]_block_invoke:4350: Got no sessions back from -[CSLSSessionService existingRunningSessions:] or -[CSLSSessionService existingScheduledSessions:] after receiving a PUICInitializeSessionServiceAction I start the workout from my phone, which successfully starts the workout on the watch. But this callback is never triggered on the phone: healthStore.workoutSessionMirroringStartHandler { // not happening } This makes it difficult to learn the mirroring workout technique. I'm using Xcode 16.3 and Mac OS 15.4.1. Any help appreciated!
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Apr ’25
What’s the expected frequency of HealthKit enableBackgroundDelivery: HKCategoryTypeIdentifier.sleepAnalysis
Hello, I have enabled HealthKit background delivery for sleep analysis samples: private func setupSleepDataBackgroundDelivery() { if let sleepType = HKObjectType.categoryType(forIdentifier: HKCategoryTypeIdentifier.sleepAnalysis) { healthStore.enableBackgroundDelivery(for: sleepType, frequency: .immediate) { (success, error) in } } } In general, this function works. But I would love to know what the limitations / expected delivery delay for frequency: .immediate is. The documentation is only very vague about this and specifies that some sample types such as steps are only delivered once per hour. But how about sleep data? Is this expected to be delivered immediately once available on iPhone? Thanks a lot for your help!
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Sep ’25
Evolution of HealthKit workout API on iOS 26 and iPadOS 26 - HKLiveWorkoutDataSource and built-in Sensor Support
I am very happy to see that HealthKit with OS26 is bringing HKLiveWorkoutDataSource to iOS and iPadOS. I have been replicating a similar type for the last several years for users that only have an iPhone. I did notice that the data types that the different platform data sources collect automatically is different. That makes sense if you think exclusively about what the device can actually capture. Bluetooth HRM is the only Bluetooth SIG profile that is out-of-the-box supported for Apple Health on iOS and iPadOS (right?). Whereas watchOS 10 got all of the cycling sensors (woohoo!). It would be great if the types to collect were the same across platforms even if the device couldn't collect the data now, because then in the future when / if new sensor support is added, it will be transparent to developers. Fantastic. Easier life as an indie / third party developer. At least that is the idea. And yes, I know I can also write Core Bluetooth code and roll my own SIG implementation for the cycling profiles, but Apple already has this code in one os, 'just copy it, it will be easy'. I know that isn't the reality especially against the new ASK framework, but one can hope and dream right? Imagine how many more apps would contribute that data if it was supported out of the box. An alternative, GitHub is a great place for Apple to share their Core Bluetooth implementation of the SIG profiles :). Just another thought. Here are some feedbacks related to this: FB17931751 - HealthKit: Add built-in support for cycling sensors on iOS and iPadOS - copy paste the code from watchOS. It will be easy they said (June 2025) FB12323089 - CoreBluetooth / Health / Bluetooth Settings: Add support for cycling sensors announced in watchOS 10 to iOS and iPadOS 17 (June 2023) FB14311218 - HealthKit: Expected outdoor cycling to include .cyclingSpeed quantity type as a default HKLiveWorkoutDataSource type to collect (July 2024) FB14978701 - Bluetooth / HealthKit / Fitness: Expose information about the user specified for Apple Watch paired Cycing Speed Sensor like isConnected and wheelCircumference values (August 2024) FB18402258 - HealthKit: HKLiveWorkoutDataSource should collect same types on iOS and watchOS even if device cannot produce data today (June 2025) FB14236080 - Developer Documentation / HealthKit: Update documentation for HKLiveWorkoutDataSource typesToCollect for which sample types are automatically collected by watchOS 10 and 11 (July 2024) Tangentially related: FB10281304 - HealthKit: Add HKActivityTypes canoeBikeRun and kayakBikeRun (June 2022) FB10281349 - HealthKit: Add HKActivityType walkCanoeWalk and walkKayakWalk (June 2022) FB7807993 - Add HKQuantityTypeIdentifier.paddleDistance for canoeing, kayaking, etc type workouts (June 2020) FB12508654 - HealthKit / Settings / Bluetooth / Workouts: Cycling sensor support doesn't allow for 'bike selection' in use case of multiple bikes and multiple sensors (borrow a bike to ride together) - production usability issue (July 2023)
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Jun ’25
HealthKit on macOS
HealthKit is currently not supported on macOS nor tvOS, despite being supported by visionOS. Support for macOS was last asked about[1] here in 2018. My goal is to display interactive data visualisations over workouts collected in HealthKit on macOS. Will this be possible to do in the near future using HealthKit directly? If not, can I somehow read the information from an iPhone and display it on the mac? Cheers, Rodrigo [1] https://developer.apple.com/forums/thread/94937
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Sep ’25
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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HealthKit quantity types are not documented when generated by the system and on which Apple Watch models
Finally at last Apple Health supports saving .distancePaddleSports, .distanceCrossCountrySkiing, .distanceRowing, .distanceSkatingSports, and much more. The backstory. In the land of 10,000 lakes, there hasn't been a way to save 'canoe' or 'kayak' distance and I've been asking for it for years. Thank you health team for adding it this year! FB7807993 - Add HKQuantityTypeIdentifier.paddleDistance for canoeing, kayaking, etc type workouts (June 2020) Prior we could just save the totalDistance to a workout, but since the HKWorkout initializers were deprecated we no longer have a supported way to save these distances in our workouts. The iOS 18 / watchOS 11 introduction addresses this. If you want to know more why you can't do this in earlier versions you can check these feedback titles: FB10281482 - HealthKit: Deprecation of totalDistance on a workout session of paddleSports breaks apps that used that to save distance to the workout because there is no "paddleDistance" type available to save as sample data (June 2022) FB12402974 - HealthKit: Deprecation of HKWorkout completely breaks support for third party fitness apps from saving non-standard workout distance (June 2023) Great, so there is new support that solves all of these requests and issues for the new version of the OSes. However, the downside is now that there is not much for documentation. Unlike the .runningSpeed and .runningPower introduced in iOS 16 / watchOS 9, none of the new iOS 18 / watchOS 11 types have documentation, at all. To some degree this is understandable, but types from last year still remain undocumented too. Without this information for the data types introduced in both iOS 17/18 and watchOS 10/11 it makes building and integrating with these new types difficult to say the least. We can't make assumptions about anything. Can we get a documentation update for new (and existing) quantity types for when Apple Watch will automatically generate samples? FB14236080 - Developer Documentation / HealthKit: Update documentation for HKLiveWorkoutDataSource typesToCollect for which sample types are automatically collected by watchOS 10 and 11 (July 2024) FB14942555 - HealthKit / Documentation: App Update Release Issue - HKQuantityTypeIdentifiers are missing documentation describing when the system automatically adds data (today) I know that the behavior has changed from release to release for some of these types, so documentation would be based on OS version. If you didn't catch it, watchOS 11 will now associate .cyclingSpeed for cycling workouts both indoor and outdoor. FB12458548 - Fitness: Connected cycling speed sensor did not save samples to health via cycling workout (June 2023 - received reply that only saved for indoor cycling, but not documented otherwise) FB14311218 - HealthKit: Expected outdoor cycling to include .cyclingSpeed quantity type as a default HKLiveWorkoutDataSource type to collect (July 2024) To the other third party fitness apps out there, how are you managing the knowledge of which devices collect which data types on which versions of the OS? Sure, we could look at the HKLiveWorkoutDatSource and inspect the typesToCollect property across a bunch of devices, but again that is trial by error not 'as documented'. Is the behavior of simulators guaranteed to match the behavior of real devices? Maybe, but also maybe not. Fingers crossed for a nice documentation update to spell out all of the behavioral details. Apple folks / DTS, many of the above feedbacks are addressed and I plan to update or close them after the releases this fall. Some are still outstanding. P.S. I hope that .paddleSports gets deprecated and split into individual activity types like skiing did years ago. Their MET scores are different according to the research on the physical activity compendium site. FB7807902 - Split HKWorkoutActivityType.paddleSports into their own activity types (June 2020)
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Dec ’24
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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Jul ’25
Stands not detected
I have FB12696743 open since July 21, 2023 and this happened again today. I get home at approx 10 mins after the hour, walk appox 50 ft across my yard, up 5 steps into my house, let the dog out and pace on my deck watching the dog, go back in the house walk around the kitchen while preparing dinner. A total of about 200 ft. I sit down about 35 past the hour and start to eat and at 10 mins to the next our and I get the reminder to stand. On the other side I wake up at 5 mins to hour. Walk 8 steps to the bathroom and successfully achieve the stand for that hour. WHY!?!?!? 😁🤣
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Jun ’25
iCloud Health data not syncing properly with iPhone Simulator on MacOS
As the title says, I logged in to iCloud on my simulator on my mac mini m2 and turned on icloud sync. My health data is in iCloud but it wont load in. When I go to documents for example I can see documents that I have loaded so I know something is working right. I have tried clicking Feature -> Trigger iCloud sync with no luck. I have tried logging out and logging back in, no luck. I have tried Restarting the simulator with no luck. The app I am building uses health data and there is no other way to get health data (heart rate, workouts, sleep) in the simulator. Please help, Thank you
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Nov ’24
Why do we still have the 7 day limitation of HealthKit data on Apple Watch?
It may have made sense in the early days of watchOS, but given the Apple Watch is now 10 years old and we have "Standalone" Apple Watch apps, it no longer makes sense to have this seemingly arbitrary limitation of only being able to query 7 days of data on the watch. I have an open feedback (FB7649612) from 2020 with no responses and ask this question every year at WWDC Developer labs. WHY must we still deal with this limitation which only causes other developers to store critical health data in iCloud or on their own servers in order to provide a robust stand alone watch experience on the Apple Watch. Even Apple themselves must either use a separate private API or use iCloud for the new Vitals app. How else can I escalate this request?
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Dec ’24
Deprecated: HKCategoryValueMenstrualFlow
We currently use the HKCategoryValueMenstrualFlow enum to determine the type of menstrual flow: light, medium, etc. a user is having. We also use this enum in determining if it's an actual period day. The Problem I see HKCategoryValueMenstrualFlow was recently deprecated but has not been replaced by another data type. Are there plans to replace/update it with another data type? When or at what point in the future will this deprecation cause a problem in my code?
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Dec ’24
Can HKWorkoutSession be used for a lone worker protection app for the Apple Watch?
We are developing a mobile app focused on lone worker protection, which does not include any fitness tracking features. We require the use of HKWorkoutSession solely to enable background execution of critical safety-related code. Could you please confirm whether this use of HKWorkoutSession is permitted under App Store Review guidelines, given that our app does not offer fitness or workout-related functionality?
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Apr ’25
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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How to save medication dose with new HealthKit apis?
The recent WWDC presentation on HealthKit demonstrated how to associate side effects with a medication dose using HKObjectType.categoryType(forIdentifier:) and HKCategorySample, a subclass of HKObject. There also appears to be an object type specifically for medication doses: HKMedicationDoseEventType, accessible via HKObjectType.medicationDoseEventType(). However, there’s no corresponding public subclass of HKObject that supports this identifier. The most relevant class, HKMedicationDoseEvent, exists but has an inaccessible initializer. Is there currently a supported way to use HKMedicationDoseEventType, or is this functionality not yet available? https://developer.apple.com/videos/play/wwdc2025/321/
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Jun ’25
AppIntent, StartWorkoutIntent, and Siri
I'm a bit confused as to what we're supposed to be doing to support starting a workout using Siri in iOS/watchOS 26. On one hand, I see a big push to move towards App Intents and shortcuts rather than SiriKit. On the other hand, I see that some of the things I would expect to work with App Intents well... don't work. BUT - I'm also not sure it isn't just developer error on my part. Here are some assertions that I'm hoping someone more skilled and knowledgable can correct me on: Currently the StartWorkoutIntent only serves the Action button on the Watch Ultra. It cannot be used to register Shortcuts, nor does Siri respond to it. I can use objects inherited from AppIntent to create shortcuts, but this requires an additional permission to run a shortcut if a user starts a workout with Siri. AppIntent shortcuts requires the user to say "Start a workout in " - if the user leaves out the "in " part, Siri will not prompt the user to select my app. If I want to allow the user to simply say "Start a Workout" and have Siri prompt the user for input as to which app it should use, I must currently use the older SiriKit to do so. Are these assertions correct - or am I just implementing something incorrectly? Using the latest Xcode 26 beta for what it is worth.
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Aug ’25
Sleep Score API access
New in iOS 26 and WatchOS 26 is a Sleep Score calculation for users based on Duration, Bedtime and Interruptions. Unfortunately I can't find any APIs for developers to tap into this metric. Yes, in theory it's all created off the same Sleep Analysis data already available with HealthKit but that makes it very hard to recreate in our apps. If the numbers don't match up exactly, users will understandably complain. Can anyone confirm that this is the case and I've not missed a Sleep Score API? I'll then file feedback. Hopefully this doesn't go the way of Heart Rate Zones where the Apple Watch iPhone app has generated them for years and provided no way for third party apps to access these values (yes many feedbacks provided previously).
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Sep ’25