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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161
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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400
Nov ’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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179
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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457
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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225
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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144
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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615
Jun ’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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181
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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126
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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110
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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135
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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95
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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161
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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188
Jun ’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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170
Jul ’25