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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Workout Types to be Added to Apple Watch
Dear Apple Developers, Could you kindly add the two following workout types to your Apple Watch? There are large communities that participate in both of these activities globally. Rucking workout option. goruck.com TRX suspension trainer option. trxtraining.com Thank you for your consideration. This addition will make many people happy.
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340
Jan ’25
HealthKit: Seeking Guidance on Continuous, Near Real-Time Heart Rate Data Conitnously in IOS Application
Dear Apple Developer Support, I am writing to request assistance with an ongoing issue I'm encountering while developing an iOS application that utilizes HealthKit to fetch heart rate data. My goal is to display near real-time heart rate updates continuously same as displaying in the Apple Watch , I want to show in the iPhone Mobile Application for fitness related. I have implemented the following approaches: HKSampleQuery with a Timer: I've set up a timer to periodically fetch the latest heart rate data. Despite these efforts, I'm consistently facing the following problems: Delayed Updates: The heart rate data displayed in the app often doesn't reflect the current heart rate being measured by the Apple Watch. There seems to be a significant synchronization delay. Inconsistent Background Updates: Background updates, even with background app refresh enabled, are not reliable. The app often only updates when brought to the foreground or after being killed and relaunched. Entitlements: The com.apple.developer.healthkit.background-delivery entitlement error is missing. I have thoroughly reviewed Apple's HealthKit documentation, implemented best practices for HealthKit integration, and verified that all necessary permissions are properly configured. I understand that HealthKit may not be designed for true real-time data, but the current level of delay and inconsistency is making it difficult to provide a useful user experience. Could you please provide guidance on whether achieving near real-time heart rate updates continuously in an iOS app using HealthKit is possible? If so, what are the recommended strategies and best practices to overcome these limitations? I have also tested the application on physical devices with Apple Watch, enabled background app refresh, granted permissions, and referred to HealthKit documentation. I would appreciate any insights or suggestions you can offer to help resolve this issue. Thank you for your time and assistance. Sincerely, Venu Madhav
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689
Feb ’25
Is it possible to provide an interface for real-time sleep status monitoring
Apple Watch automatically tracks sleep data and syncs it to the iPhone, making it available through HealthKit for historical analysis. However, there is no way to retrieve real-time data on whether a user has entered sleep, or whether they are in a specific sleep stage at any given moment. Is it possible to provide an interface for real-time sleep status monitoring
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556
Feb ’25
Request for Guidance on Cross-Platform Heart Rate Data Sharing
Dear Apple Developer Support, I hope this message finds you well. I am reaching out for guidance on a project that involves sharing heart rate data between an iOS app and an Android app. I have developed a watchOS app that continuously fetches heart rate data from an Apple Watch and displays it in a companion iOS app. Additionally, I have built an Android fitness app using Ionic Angular. My goal is to create a bridge that allows the heart rate data from the iOS app to be displayed continuously in the Android app. I am considering using a backend server (e.g., Node.js) to facilitate this data transfer. Could you please provide any insights or recommendations on the best approach for achieving this cross-platform data sharing? I would appreciate any guidance on potential challenges or limitations I might encounter. Thank you for your time and assistance. Sincerely, Venu Madhav
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460
Feb ’25
How to Save Heart Rate in HKCategoryTypeIdentifier.mindfulSession
I’m trying to associate heart rate (HR) data with a mindfulness session (HKCategoryTypeIdentifier.mindfulSession) in HealthKit, but I can’t find any documentation on how to do this. I’ve seen third-party apps (like Medito) successfully log HR within Mindful Minutes, even when the session takes place on an iPhone (not an Apple Watch). However, when I try saving HR in the metadata, it does not appear in the Health app's Mindful Minutes section. Code snippet: func logMindfulnessSession(start: Bool, heartRate: Double? = nil) { let mindfulType = HKCategoryType.categoryType(forIdentifier: .mindfulSession)! let now = Date() let endTime = now.addingTimeInterval(Double(selectedDuration)) var metadata: [String: Any]? = nil if let hr = heartRate { let heartRateUnit = HKUnit.count().unitDivided(by: HKUnit.minute()) let hrQuantity = HKQuantity(unit: heartRateUnit, doubleValue: hr) metadata = ["heartRate": hrQuantity] // ❓ Is there a correct key for HR? } let sample = HKCategorySample( type: mindfulType, value: 0, start: now, end: endTime, metadata: metadata ) healthStore.save(sample) { success, error in if let error = error { print("HealthKit session save error: \(error.localizedDescription)") } else { print("Mindfulness session saved successfully.") if let hr = heartRate { print("Saved with HR: \(hr) BPM") } } } } Questions: What is the correct metadata key for associating heart rate with a mindful session? Does HealthKit require a specific format (e.g., HKQuantitySample) for HR? 0 Are there additional permissions needed to allow HR to appear in Mindful Minutes? Does HR need to be stored separately in HKQuantityTypeIdentifier.heartRate, and if so, how do third-party apps ensure it appears in the same entry as the mindful session? thank you!
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582
Mar ’25
HKAnchoredObjectQuery Stops Receiving Updates
I implemented this to receive updates for specific data types and keep the latest daily information up to date. However, for some reason, it only works for a while before stopping completely. Background Delivery internal func backgroundDeliveryForReadTypes(enable: Bool, types: Set<HKQuantityType>) async { do { if enable { try await statusForAuthorizationRequest(toWrite: [], toRead: types) for type in types { try await healthStore.enableBackgroundDelivery(for: type, frequency: .daily) } } else { for type in types { try await healthStore.disableBackgroundDelivery(for: type) } } } catch { debugPrint("Error enabling background delivery: \(error.localizedDescription)") } } HKQueryAnchor internal var walkingActivityQueryAnchor: HKQueryAnchor? { get { if let anchorData = UserDefaults.standard.data(forKey: "walkingActivityAnchor") { return try? NSKeyedUnarchiver.unarchivedObject(ofClass: HKQueryAnchor.self, from: anchorData) } return nil } set { if let newAnchor = newValue { let anchorData = try? NSKeyedArchiver.archivedData(withRootObject: newAnchor, requiringSecureCoding: true) UserDefaults.standard.set(anchorData, forKey: "walkingActivityAnchor") } else { UserDefaults.standard.removeObject(forKey: "walkingActivityAnchor") } } } HKAnchoredObjectQuery internal func observeWalkingActivityInBackground( _ start: Bool, toRead: Set<HKQuantityType>, completion: @escaping @Sendable (Result<WalkingActivityData?, Error>) -> Void ) { if start { guard (walkingActivityQuery == nil) else { return } let predicate = getPredicate(date: Date()) let queryDescriptors = toRead.map { HKQueryDescriptor(sampleType: $0, predicate: predicate) } let handleSamples: @Sendable (HKAnchoredObjectQuery, [HKSample]?, [HKDeletedObject]?, HKQueryAnchor?, Error?) -> Void = { [weak self] _, samples, _, newAnchor, error in guard let self = self else { return } if let error = error { completion(.failure(error)) return } guard let samples = samples, !samples.isEmpty else { completion(.success(nil)) return } Task { self.walkingActivityQueryAnchor = newAnchor let activity = await self.getWalkingActivity(date: Date()) completion(.success(activity)) } } let query = HKAnchoredObjectQuery( queryDescriptors: queryDescriptors, anchor: walkingActivityQueryAnchor, limit: HKObjectQueryNoLimit, resultsHandler: handleSamples ) query.updateHandler = handleSamples healthStore.execute(query) walkingActivityQuery = query } else { if let query = walkingActivityQuery { healthStore.stop(query) walkingActivityQuery = nil } } } WalkingActivityData private func getWalkingActivity(date: Date) async -> WalkingActivityData { async let averageHeartRate = try await self.getAverageHeartRate(date: date) async let steps = try self.getStepCount(date: date) async let durationMinutes = try self.getTotalDurationInMinutes(date: date) async let distanceMeters = try self.getDistanceWalkingRunning(date: date, unit: .meter()) async let activeCalories = try self.getActiveEnergyBurned(date: date) return await WalkingActivityData( date: date, steps: try? steps, activeCalories: try? activeCalories, distanceMeters: try? distanceMeters, durationMinutes: try? durationMinutes, averageHeartRate: try? averageHeartRate ) } Example of getAverageHeartRate func getAverageHeartRate(date: Date) async throws -> Double? { let type = HKQuantityType(.heartRate) _ = try checkAuthorizationStatus(for: type) guard let heartRate = try await getDescriptor( date: date, type: type, options: .discreteAverage ).result(for: healthStore) .statistics(for: date)? .averageQuantity()?.doubleValue(for: HKUnit.count().unitDivided(by: HKUnit.minute())) else { return nil } return Double(String(format: "%.2f", heartRate)) ?? 0.0 } Descriptor & predicate internal func getPredicate(startDate: Date, endDate: Date) -> NSCompoundPredicate { let predicateForSamples = HKQuery.predicateForSamples(withStart: startDate, end: endDate) let excludeManual = NSPredicate(format: "metadata.%K != YES", HKMetadataKeyWasUserEntered) return NSCompoundPredicate(andPredicateWithSubpredicates: [predicateForSamples, excludeManual]) } internal func getDescriptor(startDate: Date, endDate: Date, type: HKQuantityType, options: HKStatisticsOptions) -> HKStatisticsCollectionQueryDescriptor { let calendar = Calendar(identifier: .gregorian) let anchorDate = calendar.date(bySetting: .hour, value: 0, of: startDate)! var interval = DateComponents() interval.day = 1 return HKStatisticsCollectionQueryDescriptor( predicate: HKSamplePredicate.quantitySample(type: type, predicate: getPredicate(startDate: startDate, endDate: endDate)), options: options, anchorDate: anchorDate, intervalComponents: interval ) } Implementation public func observeWalkingActivityInBackground(_ start: Bool, toRead: Set<HKQuantityType>, memberID: String) { observeWalkingActivityInBackground(start, toRead: toRead) { [weak self] result in guard let self = self else { return } } }
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211
Mar ’25
Querying heart rate samples hangs for some users
This is an ongoing issue that I haven't been able to solve: I am querying different types of HealthKit data over the past year. While this works fine for HRV, it hangs for some users when I'm trying to get heart rate data. Here's the relevant query func initialRead(from startDate: Date) async throws -> [HKSample] { let endDate = anchorStart let interval: TimeInterval = .days(7) var currentStartDate = startDate var currentEndDate = Date(timeInterval: interval, since: currentStartDate) var samples: [HKSample] = [] while currentStartDate <= endDate { let datePredicate = SampleType.datePredicate(start: currentStartDate, end: currentEndDate) let predicate = NSCompoundPredicate(andPredicateWithSubpredicates: [datePredicate,HKQuery.predicateForObjects(withMetadataKey: HKMetadataKeyHeartRateMotionContext, allowedValues: [HKHeartRateMotionContext.sedentary])]) do { let result = try await withCheckedThrowingContinuation { continuation in let completionQuery = HKSampleQuery(sampleType: HKQuantityType.heartRate, predicate: predicate, limit: HKObjectQueryNoLimit, sortDescriptors: [.init(key: HKSampleSortIdentifierStartDate, ascending: true)]) { query, samples, error in if let samples { continuation.resume(returning: samples) } else { if let error { continuation.resume(throwing: error) } else { continuation.resume(returning: []) } } } healthStore.execute(completionQuery) } samples = samples.merge(from: result) } catch { Logger.general.error("Reading failed for dates \(currentStartDate) to \(currentEndDate): \(error)") } currentStartDate = currentEndDate currentEndDate = Date(timeInterval: interval, since: currentStartDate) } return samples } extension HKSampleType { static func datePredicate( start:Date?, end:Date?) -> NSPredicate { HKQuery.predicateForSamples(withStart: start, end:end, options: .strictStartDate) } } For reference, I expect about 1000 sedentary samples per week. Basically what happens for these users is when they start reading the HR data, the app hangs. They start each read manually via a special TestFlight build with buttons for starting the different data type readings. Any advice on how to proceed with this bug would be great since it only affects some users. I am able to create test builds for this audience to test different options. One theory is the motion context predicate is screwing something up. If any apple dev can enlighten me how to narrow down the issue, that would be great.
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167
Mar ’25
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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72
Apr ’25
HealthKit: Real-Time Sleep Tracking with Heart Rate Data
I am trying to track a user's real-time sleep state using heart rate data, but I have encountered several issues: When using HKSampleQuery on the phone to fetch heart rate data, I can only retrieve data recorded before the app comes to the foreground or before it is terminated and restarted (see related issue: https://developer.apple.com/forums/thread/774953). I attempted to get data on the Apple Watch and send updates to the phone via Watch Connectivity. However, if I use WKExtendedRuntimeSession, although I can obtain data on the watch, once the watch screen goes off, it can no longer transmit data via Watch Connectivity to the phone (since I cannot guarantee the app will remain in the foreground when lying in bed). On the other hand, using HKWorkoutSession results in interference with the activity rings and causes the heart rate sensor to run too frequently, which I worry may affect the battery life of the watch. Is there an elegant solution for tracking a user's heart rate data for sleep monitoring?
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67
Apr ’25
Accuracy of IBI Values Measured by Apple Watch
I am currently developing an app that measures HRV to estimate stress levels. To align the values more closely with those from Galaxy devices, I decided not to use the heartRateVariabilitySDNN value provided by HealthKit. Instead, I extracted individual interbeat intervals (IBI) using the HKHeartBeatSeries data. Can I obtain accurate IBI data using this method? If not, I would like to know how I can retrieve more precise data. Any insights or suggestions would be greatly appreciated. Here is a sample code I tried. @Observable class HealthKitManager: ObservableObject { let healthStore = HKHealthStore() var ibiValues: [Double] = [] var isAuthorized = false func requestAuthorization() { let types = Set([ HKSeriesType.heartbeat(), HKQuantityType.quantityType(forIdentifier: .heartRateVariabilitySDNN)!, ]) healthStore.requestAuthorization(toShare: nil, read: types) { success, error in DispatchQueue.main.async { self.isAuthorized = success if success { self.fetchIBIData() } } } } func fetchIBIData() { var timePoints: [TimeInterval] = [] var absoluteStartTime: Date? let dateFormatter = DateFormatter() dateFormatter.timeZone = TimeZone(identifier: "Asia/Seoul") dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss.SSS" var calendar = Calendar.current calendar.timeZone = TimeZone(identifier: "Asia/Seoul") ?? .current var components = DateComponents() components.year = 2025 components.month = 4 components.day = 3 components.hour = 15 components.minute = 52 components.second = 0 let startTime = calendar.date(from: components)! components.hour = 16 components.minute = 0 let endTime = calendar.date(from: components)! let predicate = HKQuery.predicateForSamples(withStart: startTime, end: endTime, options: .strictStartDate) let sortDescriptor = NSSortDescriptor(key: HKSampleSortIdentifierStartDate, ascending: false) let query = HKSampleQuery(sampleType: HKSeriesType.heartbeat(), predicate: predicate, limit: HKObjectQueryNoLimit, sortDescriptors: [sortDescriptor]) { (_, samples, _) in if let sample = samples?.first as? HKHeartbeatSeriesSample { absoluteStartTime = sample.startDate let startDateKST = dateFormatter.string(from: sample.startDate) let endDateKST = dateFormatter.string(from: sample.endDate) print("series start(KST):\(startDateKST)\tend(KST):\(endDateKST)") let seriesQuery = HKHeartbeatSeriesQuery(heartbeatSeries: sample) { query, timeSinceSeriesStart, precededByGap, done, error in if !precededByGap { timePoints.append(timeSinceSeriesStart) } if done { for i in 1..<timePoints.count { let ibi = (timePoints[i] - timePoints[i-1]) * 1000 // Convert to milliseconds // Calculate absolute time for current beat if let startTime = absoluteStartTime { let beatTime = startTime.addingTimeInterval(timePoints[i]) let beatTimeString = dateFormatter.string(from: beatTime) print("IBI: \(String(format: "%.2f", ibi)) ms at \(beatTimeString)") } self.ibiValues.append(ibi) } } } self.healthStore.execute(seriesQuery) } else { print("No samples found for the specified time range") } } self.healthStore.execute(query) } }
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64
Apr ’25
Synchronization Timing Between Apple Watch HealthKit Store and iPhone HealthKit Store
Hi, I’m currently working on an app that utilizes sleep data from HealthKit to provide users with meaningful insights about their sleep. To ensure a smooth user experience, I’d like to understand when sleep data collected by the Apple Watch is saved to the HealthKit store and when it gets synced to the iPhone. Ideally, I want to fetch sleep data right after the user wakes up and opens our app. However, to do this reliably, I need to know the timing of how and when this data becomes available in the iPhone’s HealthKit store. I’ve looked through the official documentation and relevant WWDC sessions but couldn’t find clear information on this topic. If anyone has insights or experience with how and when the Apple Watch syncs HealthKit data—especially sleep records—to the iPhone, I’d greatly appreciate your input. Thanks!
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75
Apr ’25
Detecting Sleep End Events and Sleep Data Sync Timing from Apple Watch to HealthKit on iPhone
Hello, I’m developing an iOS app that works with sleep data from Apple Watch via HealthKit. I would like to clarify the following: How can an iPhone app detect when a sleep session ends on the Apple Watch? When is sleep data typically written to the HealthKit store on iPhone after sleep ends? Is it immediately after wake-up, or does it depend on certain conditions (e.g., watch charging, connectivity)? Understanding the timing and mechanism of sleep data synchronization is crucial for our app to process accurate and timely health information. Thank you for your assistance.
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42
Apr ’25
Non-ViewModifier way to present WorkoutPlan preview
Hello, is there a way to present WorkoutPlan preview just like it was presented on WWDC video: https://developer.apple.com/videos/play/wwdc2023/10016/ with WorkoutCompositions? Or was this way ditched completely and is not possible to reproduce anymore? I find it weird that this view modifier accepts non-optional WorkoutPlan when the process of creating one can fail for many reasons with fatalError (that's another issue - why isn't there throws used anywhere?) when not checked with dedicated methods and I think that it would make more sense to create WorkoutPlan when user completes filling some kind of form. Because right now it's needed to compute the non-optional WorkoutPlan for the sake of .workoutPreview modifier live for any changes and that can often lead to errors. Non-modifier way of presenting the preview, like the one presented on WWDC would work really well for my project
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101
Jun ’25
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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64
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