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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Old HealthKit samples from WatchOS getting deleted and recreated years later
I have recently come across a couple of odd HealthKit step samples from WatchOS. They represent step data measured in 2022 by my Apple Watch, but they have a creation date ("Date Added to Health") within the past couple of days. These odd samples show a "View All Quantities" button at the bottom of the sample Details page in the Health app on iOS 26 (which I've never seen before); the button leads to a list of many small step quantities, almost as if some older, smaller samples were consolidated into these newer samples. Even weirder is that at least some of these samples seem to be getting re-created repeatedly. For example, I've seen the same sample with a "Date Added to Health" of 9/5/25, then 9/8/25, twice on 9/9/25, and twice on 9/10/25. These samples were originally created by WatchOS 9, and are not being deleted/recreated by any apps on my device. I have only observed it since I updated to the iOS 26 beta (and now the RC); my watch was still running iOS 18 the first time it happened, but it has also happened since my watch was updated to WatchOS 26 beta. I did some debug printing of the odd samples and the normal samples surrounding them for comparison. Here's a normal sample: Sample: 80AC5AC5-CBD7-4581-B275-0C2ACA35B7B4 6 count 80AC5AC5-CBD7-4581-B275-0C2ACA35B7B4, (9.0), "Watch6,1" (9.0) "Apple Watch" (2022-09-15 16:20:14 -0500 - 2022-09-15 16:20:16 -0500) Device: <<HKDevice: 0x10591eee0>, name:Apple Watch, manufacturer:Apple Inc., model:Watch, hardware:Watch6,1, software:9.0, creation date:2022-08-25 18:22:26 +0000> Source revision: <HKSourceRevision name:My Apple Watch, bundle:com.apple.health.EE83959D-D009-4BA0-83A5-2E5A1CC05FE6, version:9.0, productType:Watch6,1, operatingSystemVersion:9.0> Source: <HKSource:0x110588690 "My Apple Watch", bundle identifier: com.apple.health.EE83959D-D009-4BA0-83A5-2E5A1CC05FE6, localDeviceSource: 0, modification date: 2024-01-31 05:49:18 +0000> Date added: 2022-09-15 21:20:16 +0000 Days between end and add: 0 And here's one of the odd samples: Sample: 4982487F-1189-4F16-AB00-61E37818A66D 676 count 4982487F-1189-4F16-AB00-61E37818A66D, (9.0), "iPhone12,1" (16.2) "Apple Watch" metadata: { HKMetadataKeySyncIdentifier = "6:38082859-D9C8-466A-8882-53443B2A2D94:684969619.25569:684970205.31182:119"; HKMetadataKeySyncVersion = 1; } (2022-09-15 16:20:19 -0500 - 2022-09-15 16:30:05 -0500) Device: <<HKDevice: 0x10591ce40>, name:Apple Watch, manufacturer:Apple Inc., model:Watch, hardware:Watch6,1, software:9.0, creation date:2022-08-25 18:22:26 +0000> Source revision: <HKSourceRevision name:My Apple Watch, bundle:com.apple.health.EE83959D-D009-4BA0-83A5-2E5A1CC05FE6, version:9.0, productType:iPhone12,1, operatingSystemVersion:16.2> Source: <HKSource:0x110588640 "My Apple Watch", bundle identifier: com.apple.health.EE83959D-D009-4BA0-83A5-2E5A1CC05FE6, localDeviceSource: 0, modification date: 2024-01-31 05:49:18 +0000> Date added: 2025-09-08 21:11:12 +0000 Days between end and add: 1088 Here's that same odd sample a day later, apparently recreated: Sample: 9E8B12FC-048D-4ECD-BE5B-D387AADE5130 676 count 9E8B12FC-048D-4ECD-BE5B-D387AADE5130, (9.0), "iPhone12,1" (16.2) "Apple Watch" metadata: { HKMetadataKeySyncIdentifier = "6:38082859-D9C8-466A-8882-53443B2A2D94:684969619.25569:684970205.31182:119"; HKMetadataKeySyncVersion = 1; } (2022-09-15 16:20:19 -0500 - 2022-09-15 16:30:05 -0500) Device: <<HKDevice: 0x12f01c4e0>, name:Apple Watch, manufacturer:Apple Inc., model:Watch, hardware:Watch6,1, software:9.0, creation date:2022-08-25 18:22:26 +0000> Source revision: <HKSourceRevision name:My Apple Watch, bundle:com.apple.health.EE83959D-D009-4BA0-83A5-2E5A1CC05FE6, version:9.0, productType:iPhone12,1, operatingSystemVersion:16.2> Source: <HKSource:0x12f0f8230 "My Apple Watch", bundle identifier: com.apple.health.EE83959D-D009-4BA0-83A5-2E5A1CC05FE6, localDeviceSource: 0, modification date: 2024-01-31 05:49:18 +0000> Date added: 2025-09-09 20:53:18 +0000 Days between end and add: 1089 It's worth pointing out some differences between the "normal" and "odd" samples (besides the "View All Quantities" button in the Health app). The recreated "odd" samples have a different Source Revision - the "productType" and "operatingSystemVersion" refer to my iPhone, not the Apple Watch device that actually captured the samples. The odd samples also have metadata keys that don't exist in the other samples - HKMetadataKeySyncIdentifier and HKMetadataKeySyncVersion. Questions I'm hoping someone can help with: What are these samples? Why/how do they have a "View All Quantities" button that shows sub-samples? Is this new to iOS 26? Why are some of the samples getting recreated multiple times?
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155
Sep ’25
Icon Composer - Icon not visible in Fitness App
Hi everyone, we’re developing an app that lets users export selected bike rides to the HealthKit ecosystem. We created our app icon using the Apple Icon Composer and referenced the composer file in Xcode. Everything works fine, except that the logo doesn’t appear correctly in the Fitness app. Has anyone experienced this issue or knows how to fix it?
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294
Nov ’25
HKLiveWorkoutBuilder begincollection freezes in WatchOS simulator
The second time i start a workout session, the beginCollection instance method on HKLiveWorkoutBuilder freezes. To recreate run the Apple Sample Project Building a multidevice workout app. It looks like a bug with the HealthKit SDK and not the code but i could be wrong. The only workaround i found was erasing the simulator and reinstalling the app.
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157
Dec ’25
Perfect month award fitness app on iPhone
Hi! I have over 800 days strike in closing my move circle. However oerfect month badge is not popping up for November, we have now mid of Dec and still no update. I updated iOS to 26, did multiple resets and hard resets and still no badge. I checked many forums and post but any of given tips is working in my case. i know it sounds funny, but it’s frustrating that I’m not getting this little gold medal to keep me motivated 😅 does anyone know how to deal with it? Is it common issue?
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140
Dec ’25
Bug apple Health
Hello everyone, I’m experiencing a visual issue when dismissing a sheet on iOS 26. I’m using the same implementation shown in the official Apple documentation. While testing, I noticed that some apps do not exhibit this behavior. However, when running this code on iOS 26, the issue consistently occurs. Issue description: The sheet dismisses abruptly A white screen briefly appears for a few milliseconds and then disappears This results in a noticeable visual glitch and a poor user experience I tested the exact same code on iOS 18, where the sheet dismisses smoothly and behaves as expected, without any visual artifacts. Has anyone else encountered this issue on iOS 26? Is this a known bug, or is there a recommended workaround? Any insights would be greatly appreciated. Thank you.
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339
Dec ’25
How to detect when Apple Watch is removed from wrist during active workout session?
I'm currently collecting real-time heart rate data using HKWorkoutSession. I want to track when the Apple Watch is physically removed from the user's wrist during an active workout. However, I've noticed that workoutBuilder(_:didCollectDataOf:) continues to be called even after the watch is removed from the wrist. Is there a way to detect when the Apple Watch is removed from the wrist during an active HKWorkoutSession? Or is this tracking not possible through the HealthKit framework? Any guidance or alternative approaches would be appreciated.
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177
Jan ’26
Treadmill integration and weighted vest with HealthKit
I don't understand why elevation data is not stored in the sample using a standard length unit. Why is it stored in HKQuantityTypeIdentifier.flightsClimbed (which is 10 feet)? Surely it is not a memory usage issue. Treadmill GATT provides elevation in meters. Using HKMetadataKeyElevationAscended for the total elevation gain throws away a lot of data. Why is there no support for weighted vest or backpack? Changing body weight is not the same and provides incorrect energy. Users want to compare workouts with different weights. I don't see any metadata key for carried weight.
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98
Jan ’26
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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589
Jun ’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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799
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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635
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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663
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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795
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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341
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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225
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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153
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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121
Apr ’25