Use HealthKit to enable your iOS and watchOS apps to work with the Apple Health app.

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Real-Time WatchConnectivity Sync Not Working Between iPhone and Apple Watch
Hi everyone, I'm building a health-focused iOS and watchOS app that uses WatchConnectivity to sync real-time heart rate and core body temperature data from iPhone to Apple Watch. While the HealthKit integration works correctly on the iPhone side, I'm facing persistent issues with WatchConnectivity — the data either doesn't arrive on the Watch, or session(_:didReceiveMessage:) never gets triggered. Here's the setup: On iPhone: Using WCSession.default.sendMessage(_:replyHandler:errorHandler:) to send real-time values every few seconds. On Apple Watch: Implemented WCSessionDelegate, and session(_:didReceiveMessage:) is supposed to update the UI. Both apps have WCSession.isSupported() checks, activate the session, and assign delegates correctly. The session state shows isPaired = true and isWatchAppInstalled = true. Bluetooth and Wi-Fi are on, both devices are unlocked and nearby. Despite all this, the Watch never receives messages in real-time. Sometimes, data comes through in bulk much later or not at all. I've double-checked Info.plist configurations and made sure background modes include "Uses Bluetooth LE accessories" and "Background fetch" where appropriate. I would really appreciate guidance on: Best practices for reliable, low-latency message delivery with WatchConnectivity. Debugging steps or sample code to validate message transmission and reception. Any pitfalls related to UI updates from the delegate method. Happy to share further details. Thanks in advance!
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67
Jun ’25
Apple Watch Data to Server
I was wondering which is the preferred way to send a lot of data from sensors of the apple watch to server. It is preferred to send small chucks to iphone and then to server or directly send bulk data to server from watch. How does it affect battery and resources from watch ? Are there any triggers that I can use to ensure best data stream. I need to send at least once a day. Can I do it in background or do I need the user to have my app in the foreground ? Thank you in advance
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95
Jun ’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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163
Jul ’25
Workout Buddy not available
Has anyone seen the workout buddy options on watch OS yet? I am not able to get it on my watch. My setup is an iPhone 16 and Watch Ultra 1 with the 26 OS I am currently using beta 3. English US language on both and US as region. I am located in Germany though. I restarted both devices multiple times without any changes. Hopefully someone can help.
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60
Jul ’25
HKLiveWorkoutBuilder get wrong calorie data for iOS 26
In iOS 26, HKLiveWorkoutBuilder is supported, which we can use like HKWorkoutSession in watchOS - this is very exciting. However, it currently seems to have a bug in calculating calories. I tested it in my app, and for nearly 6 minutes with an average heart rate of 134, it only calculated 8 calories consumed (80 calories per hour), including basal consumption, which is obviously incorrect. (I used Powerboats Pro 2 connected to my phone, which includes heart rate data, and HKLiveWorkoutBuilder correctly collected the heart rate, which is great.) I think my code is correct. func workoutBuilder(_ workoutBuilder: HKLiveWorkoutBuilder, didCollectDataOf collectedTypes: Set<HKSampleType>) { for type in collectedTypes { guard let quantityType = type as? HKQuantityType else { return // Nothing to do. } let statistics = workoutBuilder.statistics(for: quantityType) if let statistics = statistics { switch statistics.quantityType { case HKQuantityType.quantityType(forIdentifier: .heartRate): /// - Tag: SetLabel let heartRateUnit = HKUnit.count().unitDivided(by: HKUnit.minute()) let value = statistics.mostRecentQuantity()?.doubleValue(for: heartRateUnit) let roundedValue = Double( round( 1 * value! ) / 1 ) if let avg = statistics.averageQuantity()?.doubleValue(for: heartRateUnit) { self.avgHeartRate = avg } self.delegate?.didUpdateHeartBeat(self, heartBeat: Int(roundedValue)) case HKQuantityType.quantityType(forIdentifier: .activeEnergyBurned): let energyUnit = HKUnit.kilocalorie() let value = statistics.sumQuantity()?.doubleValue(for: energyUnit) self.totalActiveEnergyBurned = Double(value!) print("didUpdate totalActiveEnergyBurned: \(self.totalActiveEnergyBurned)") self.delegate?.didUpdateEnergyBurned(self, totalEnergy: self.totalActiveEnergyBurned + self.totalBasalEneryBurned) return case HKQuantityType.quantityType(forIdentifier: .basalEnergyBurned): let energyUnit = HKUnit.kilocalorie() let value = statistics.sumQuantity()?.doubleValue(for: energyUnit) self.totalBasalEneryBurned = Double(value!) print("didUpdate totalBasalEneryBurned: \(self.totalBasalEneryBurned)") self.delegate?.didUpdateEnergyBurned(self, totalEnergy: self.totalActiveEnergyBurned + self.totalBasalEneryBurned) return default: print("unhandled quantityType=\(statistics.quantityType) when processing statistics") return } } I think I've found the source of the problem: let workoutConfiguration = HKWorkoutConfiguration() workoutConfiguration.activityType = .traditionalStrengthTraining //walking, running is ok workoutConfiguration.locationType = .outdoor When I set the activityType to walking or running, the calorie results are correct, showing several hundred calories per hour. However, when activityType is set to traditionalStrengthTraining or jumprope, the calculations are incorrect. PS: I'm currently using Xcode 26 beta3 and iOS 26 beta3. Hope this issue can be resolved. Thanks.
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95
Jul ’25
Best Practices for Continuous Background Biometric Monitoring on Apple Watch
Hello, everyone! I'm seeking some guidance on the App Store review process and technical best practices for a watchOS app. My goal is to create an app that uses HealthKit to continuously monitor a user's heart rate in the background for sessions lasting between 30 minutes and 3 hours. This app would not be a fitness or workout tracker. My primary question is about the best way to achieve this reliably while staying within the App Store Review Guidelines. Is it advisable to use the WorkoutKit framework to start a custom, non-fitness "session" for the purpose of continuous background monitoring? Are there any other recommended APIs or frameworks for this kind of background data collection on watchOS that I should be aware of? What are the key review considerations I should be mindful of, particularly regarding Guideline 4.1 (Design) and the intended use of APIs? My app's core functionality would require this kind of data for a beneficial purpose. I want to ensure my approach is technically sound and has the best chance of a successful review. Any insights or advice from developers who have experience with similar use cases would be incredibly helpful! Thank you!
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3w
HKAnchoredObjectQuery updateHandler stops working with error
Hi! I am using the HKAnchoredObjectQuery to first get a snapshot of the initial results, and then trigger an updateHandler. I need to handle the initial results and the updates separately, which is why I implemented two completions. When I test the code, it works for a while. New and deleted samples trigger the updateHandler. However, after a while there appears an error: [connection] nw_read_request_report [C2] Receive failed with error "Software caused connection abort" Followingly, the updateHandler will stop getting triggered when I add updates in Apple health. Anyone have experience with this? func getMostRecentSample(for sampleType: HKSampleType, anchorKey: String, completion: @escaping (HKQuantitySample?, Error?) -> Swift.Void, updateHandler: @escaping (HKQuantitySample, Error?) -> Swift.Void) {     // If it is the first initialization, anchor is passed as nil     var anchor: HKQueryAnchor? = nil // Check for previous saved anchor in userdefaults     if UserDefaults.standard.object(forKey: anchorKey) != nil {       let data = UserDefaults.standard.object(forKey: anchorKey) as! Data       do {         guard let newAnchor = try NSKeyedUnarchiver.unarchivedObject(ofClass: HKQueryAnchor.self, from: data) else {           print("Could not parse anchor to HKQueryAnchor type")           return         }         anchor = newAnchor       } catch {         print("Error retreiving anchor from UserDefaults")       }     }     let query = HKAnchoredObjectQuery(type: sampleType,                      predicate: nil,                      anchor: anchor,                      limit: HKObjectQueryNoLimit                       ) { (query, samplesOrNil, _, newAnchor, errorOrNil) in       guard let samples = samplesOrNil as? [HKQuantitySample] else {         fatalError("*** An error occurred during the initial query: \(errorOrNil!.localizedDescription) ***")       }       if let anchor = newAnchor {         do {           let data = try NSKeyedArchiver.archivedData(withRootObject: anchor as Any, requiringSecureCoding: false)           UserDefaults.standard.set(data, forKey: anchorKey)         } catch {           print("Error retreiving anchor from UserDefaults")         }       }       completion(samples.last, nil)     }           // Setting up long-running query     query.updateHandler = { (query, samplesOrNil, _, newAnchor, errorOrNil) in       guard let samples = samplesOrNil as? [HKQuantitySample] else {         fatalError("*** An error occurred during an update: \(errorOrNil!.localizedDescription) ***")       }       if let anchor = newAnchor {         do {           let data = try NSKeyedArchiver.archivedData(withRootObject: anchor as Any, requiringSecureCoding: false)           UserDefaults.standard.set(data, forKey: anchorKey)         } catch {           print("Error retreiving anchor from UserDefaults")         }       }       if let sample = samples.last {         updateHandler(sample, nil)       }     }     self.healthStore.execute(query)   }
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1.1k
Mar ’25
How to add "Estimated Time in Each Heart Rate Zone" info to my custom HKWorkout when viewed in Apple Fitness app?
Hello, I’m currently developing a fitness app for watchOS that lets a user to manually set a desired heart rate target zone (enter numbers representing the lower and upper boundaries) and start a workout (right now it’s only “Other” type). After that my app monitors user’s heart rate and alerts them when they’re out of zone. When user ends the workout, the info about this workout appears on “Fitness” iOS app, and user can see the workout data like Workout Time, Active and Total Calories, Avg. Heart Rate. Also user can see Heart Rate chart with info how their heart rate was changing during a workout (see the Figure 1). Now to the question. When user clicks “Show More” button above the Heart Rate chart, they can see the same Heart Rate chart and another one, with Post-Workout Heart Rate (see the Figure 2). But there is no “Estimated time in each heart rate zone” as one can see in the workout’s details that were recorded from Apple’s workout (watchOS “Workout” app, for a workout of “Other” type as well). Please see the Figure 3. The question is: is it possible to add “Estimated time in each heart rate zone” to workout recorded via my third-party app so it would look like on the Figure 3 in "Fitness" iOS app, and if it's possible, what steps should I undertake to implement this ? Thanks in advance! I posted the screenshots in the replies to the post, because otherwise I was not able to submit a post ("sensitive language" warning, I suspect it's because of the ids in the attached screenshot's urls)
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1.2k
Oct ’24
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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853
Dec ’24
Mirroring Workouts Sample Code Doesn't Work With Simulators
I've realised with the sample code from the WWDC video below I'm getting the following error when trying to use the iPhone simulator and apple watch simulator paired. Whenever i try to test out the sample project I'm getting the following error. Failed to send data: Error Domain=com.apple.healthkit Code=300 "Remote device is unreachable" UserInfo={NSLocalizedDescription=Remote device is unreachable, NSUnderlyingError=0x600000c9c900 {Error Domain=RPErrorDomain Code=-6727 "kNotFoundErr ('rapport:rdid:PairedCompanion' not found)" UserInfo={cuErrorDesc=kNotFoundErr ('rapport:rdid:PairedCompanion' not found), cuErrorMsg='rapport:rdid:PairedCompanion' not found, NSLocalizedDescription=kNotFoundErr ('rapport:rdid:PairedCompanion' not found)}}} Is it not possible to not test out the new WorkoutKit mirroring API's using the simulator? Currently right now if you run the project you'll notice that you can start a workout session on the iPhone > Apple Watch but there is no way to control and mirror on both devices at the moment i.e You can't control the iPhone app on the Apple Watch and vice versa. Also because of this the iPhone can't send data to the Apple Watch i.e. pause, end, water etc. I'm guessing this is meant to be possible since it seems a bit strange to only be able to test this out with actual devices. WWDC Session https://developer.apple.com/wwdc23/10023 Sample Code https://developer.apple.com/documentation/healthkit/workouts_and_activity_rings/building_a_multidevice_workout_app
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876
Oct ’24
HealthKit data - Is HKStatisticsCollectionQuery slow?
Hi, I am using HealthKit for the first time. I am using HKStatisticsCollectionQuery. I am running my code iOS 17 on a physical iPhone. It takes several seconds to query data, for example 1 day worth of heart rate at 1 minute resolution. I changed the resolution to 1 hour, expecting it to be faster, but it's pretty much the same… I have been following the official documentation and sample code. I also compiled in Release, but that didn't really help for HKStatisticsCollectionQuery. I quickly looked with Instruments, the app is spending a lot of time in decoding data with NSXPCDecoder. Is there a way to speed data retrieval? Or this is "expected" latency?
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1k
Oct ’24
Run Application In The Background Automation
I’ve developed an automation and shortcut using the iPhone Shortcuts app in IOS 18, something that hasn’t been done before. With support from Apple’s customer service, I was encouraged to bring this idea to life. The automation’s purpose is to open a specified iOS app, move it to the background, and use a txt database in Folders to ensure uninterrupted data flow and continuous connectivity—especially useful for health apps where wearable devices need consistent, uninterrupted operation and monitoring (e.g., doctor tracking or wearable device connectivity). I would like to share the Automation and the Shortcut with the community.
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943
Oct ’24
Unable to access details page for vehicle crash entitlement (SafetyKit)
Hi, I am part of a team working to incorporate vehicle crash detection using SafetyKit. However, I am unable to know more details about this entitlement since the details page (https://developer.apple.com/contact/request/vehicular-crash-events/) is showing an unauthorised message as shown in the image below. All the latest licenses have been reviewed and agreed to. Please let me know what can be done to access this link and know the details of this entitlement.
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385
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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931
Dec ’24
Read Workout Effort Scores
Is there documentation on how to read workout effort scores from a HealthKit workout? I'm interested in reading workoutEffortScore and estimatedWorkoutEffortScore. I have not been successful trying to read them using the same method that I do other workout HKQuantityTypes (heartRate, stepCount, etc). I'm using Swift and I do have authorization for those types requested and granted. I have found documentation on setting these values (https://developer.apple.com/forums/thread/763539) but not reading them. Thank You
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911
Jan ’25
Workouts fail to register on Fitness activity rings
Hello, My app syncs workout data from a third-party device and records workouts with HealthKit as follows: let builder = HKWorkoutBuilder(healthStore: healthStore, configuration: hkConf, device: hkDevice) try await builder.beginCollection(at: startDate) try await builder.addSamples(samples) try await builder.endCollection(at: endDate) let workout = try await builder.finishWorkout() let workoutRouteBuilder = HKWorkoutRouteBuilder(healthStore: healthStore, device: hkDevice) try await workoutRouteBuilder.insertRouteData(filteredLocations) try await workoutRouteBuilder.finishRoute(with: workout, metadata: nil) However, I’m encountering two issues: The workouts appear in Apple Fitness but do not contribute to the activity rings. The workout includes a route (visible in the raw workout data in Apple Health) but does not display on Apple Fitness. Is there any way to fix this? I’d appreciate any suggestions you might have. __
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747
Jan ’25
Extended Runtime Session vs HKWorkoutSession Issues
I am working on an Apple Watch companion app to an existing live iOS app. I am utilizing the heart rate tracking for an active 'self-care' sauna session. I say self-care in quotes because it's more self-care than a workout activity, but it is closely blurring the lines between the two. I have come to understand that if a session truly isn't a workout, then you should not use workoutSession.startActivity. However the app needs to function entirely like a workout would. This is not a meditation application. Sauna is actually just one of many activity types supported in the app. I have tried using extended runtime session, and there have been numerous issues with doing so. It is not nearly as robust for the user. For example, the active session is not prioritized by the watch's CPU. Now playing is no longer functional. Heart rate is far more inconsistent, and this variable is as critical as if it were in a workout. I have tried using HKWorkoutSession, however I worry the app will be rejected by doing so. This method works most accurately to collect the right data for the user, and prioritizes system resources as expected. The app can be moved to the background as expected and continue to communicate with the iOS app. What is the best way to move forward here. It almost feels like I am operating in a grey area with no real solution in place. Any assistance is greatly appreciated as we would like to follow all guidelines while producing a high quality experience for our users.
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793
Jan ’25
Location of indoor workouts
In the fitness app under iOS 18, the location of all workouts is displayed on a small map. For workouts with routes, I can already successfully read out the route and thus also determine the starting point. So that works. For indoor workouts such as yoga or indoor rowing, the exact location is also displayed in the fitness app. I would now also like to read out this location for these indoor workouts in my app. Does anyone know how to do this?
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800
Apr ’25
怎样读取健康记录心理状态的情境,并将自己APP的数据传入进去
读取是不是解析 metadata 的对应键来获取值对吧~但我看了相关开发文档好像没找到这个的键是什么~于是也没法写入到对应的,现在只能自定义键来进行写入 但是这样写入后无法显示在心情下方的影响因素后面~ 这个 key 是没公开的吗还是说我方法弄错了~请各位大大指教
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68
May ’25