I’m running into a hardware reality. MEMS sensor thermal drift. If a user zeroes out the tilt indoors at 20°C and then takes the phone outside in the cold, the accelerometer baseline shifts just enough as the device cools to throw off the readings. I want to apply a simple thermal compensation curve to the CoreMotion data to keep the "zero" perfectly level regardless of the weather. However, ProcessInfo.thermalState only gives broad buckets (nominal, fair, etc.) which doesn't help me calculate a continuous offset for a phone cooling down degree by degree. Is there any public API, or even a proxy metric, that can give me a rough battery or internal temperature integer? I don’t need high resolution decimals. Just a general device temp to offset the hardware drift. Any undocumented tricks or proxy metrics anyone has used to handle this?

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!

Hello, Recently we got a question about the event_timestamps for the phone usage report in our research project: Does the event_timestamp correspond to the start point or end point of a period of interest? For example, say the event_timestamp is 2024-07-01 23:59:59 with a duration of 86400. The user is noted to have made 2 phone calls during that event_timestamp. Did those phone calls occur in the 86400 seconds prior to that timestamp (i.e., on 2024-07-01) or in the 86400 seconds after that timestamp (i.e., on 2024-07-02)? Thanks!

Hello, I am currently developing an iOS application using SensorKit. I encountered an issue when attempting to fetch SensorKit data in the background using background tasks (appRefresh, processing). The following error occurs: In the delegate function func sensorReader(_ reader: SRSensorReader, fetching fetchRequest: SRFetchRequest, failedWithError error: any Error) {}, I receive the error: SRErrorDataInaccessible. In code specific manner: start and handle background fetch (appRefresh) func handleAppRefreshTask(task: BGAppRefreshTask) { logger.logWithServer(level: .default, message: "background fetch start", category: String(describing: BackgroundTaskManager.self)) scheduleBackgroundFetch() let queue = OperationQueue() queue.maxConcurrentOperationCount = 1 let fetchOperation = FetchOperation() queue.addOperation(fetchOperation) task.expirationHandler = { self.logger.logWithServer(level: .error, message: "background fetch expirated", category: String(describing: BackgroundTaskManager.self)) queue.cancelAllOperations() } fetchOperation.completionBlock = { task.setTaskCompleted(success: !fetchOperation.isCancelled) } } Background fetch operation class class FetchOperation: Operation { override func main() { guard !isCancelled else { return } Task { // this function will execute fetch request for all user allowed sensorReader, 'func fetch(_ request: SRFetchRequest)' await SensorkitManager.shared.startFetchAndUpload() } } } I have the following questions: Is it possible to fetch SensorKit data in the background? If it is possible, why does the above error occur? If it is possible, could you provide the solution code and the correct workflow to avoid this error? Thank you.

Dear Apple Team, I’m a high school student (vocational upper secondary school) working on my final research project about LiDAR sensors in smartphones, specifically Apple’s iPhone implementation. My current understanding (for context): I understand Apple’s LiDAR uses dToF with SPAD detectors: A VCSEL laser emits pulses, a DOE splits the beam into a dot pattern, and each spot’s return time is measured separately → point cloud generation. My specific questions: How many active projection dots does the LiDAR projector have in the iPhone 15 Pro vs. iPhone 12 Pro? Are the dots static or do they shift/move over time? How many depth measurement points does the system deliver internally (after processing)? What is the ranging accuracy (cm-level precision) of each measurement point? Experimental background: Using an IR night vision camera, I counted approximately 111 dots on the 15 Pro vs. 576 dots on the 12 Pro. Do these match the internal specifications? Photos of my measurements are available if helpful. Contact request: I would be very grateful if you could connect me with an Apple engineer or ARKit specialist who works with LiDAR technology. I would love to ask follow-up questions directly and would be happy to provide my contact details for this purpose. These specifications would be essential for my research paper. Thank you very much in advance! Best regards, Max! Vocational Upper Secondary School Hans-Leipelt-Schule Donauwörth Research Project: “LiDAR Sensor Technology in Smartphones”

We tried to fetch the recorded PPG data using SensorKit with the following code, however the didFetchResult callback method is never called. let ppgReader = SRSensorReader(sensor: .photoplethysmogram) let request = SRFetchRequest() let nowDate = Date() let toDate = nowDate.addingTimeInterval(-25 * 60 * 60) let fromDate = toDate.addingTimeInterval(-24 * 60 * 60) request.from = SRAbsoluteTime.fromCFAbsoluteTime(_cf: fromDate.timeIntervalSinceReferenceDate) request.to = SRAbsoluteTime.fromCFAbsoluteTime(_cf: toDate.timeIntervalSinceReferenceDate) ppgReader.delegate = self; ppgReader.fetch(request) The delegate called the didComplete successfully: func sensorReader(_ reader: SRSensorReader, didCompleteFetch fetchRequest: SRFetchRequest) But never called the didFetchResult func sensorReader(_ reader: SRSensorReader, fetching fetchRequest: SRFetchRequest, didFetchResult result: SRFetchResult<AnyObject>) -> Bool Any ideas why ? (I am wearing the watch for couple days and ensure it has the data for the time period I am querying) One thing I notice is when Apple granted us the entitlement, it uses Uppercase for ECG and PPG, however the document use Lowercases in the plist https://developer.apple.com/documentation/sensorkit/srsensor/photoplethysmogram Dose it matter ?

From the document https://developer.apple.com/documentation/sensorkit/srfetchrequest we know that "SensorKit places a 24-hour holding period on newly recorded data before an app can access it. This gives the user an opportunity to delete any data they don’t want to share with the app. A fetch request doesn’t return any results if its time range overlaps this holding period." Will this holding period reset each time when I called startRecording() ? Let's say I upgrade my app to a new version, do I need to call startRecording again to init the data collection process? will it be able to query the data collected from previous version's app ?

Hello, Recently we got a question about the keyboard sensor data collection in our research project: "For the typing statistics, was any typing included or only messaging and notes? E.g., typing in the browser, phone search, calendar, etc?" While I believe it should be any typing included, I was not able to find a document explicitly stating that. Could you help to confirm it or guide me to any documentation explaining it? Thanks!

Hello, I'm currently developing an iOS app that uses SensorKit. Everything works fine in development and testing — the app correctly requests and receives SensorKit permissions on test devices. In my App ID configuration, the SensorKit Reader Access entitlement (com.apple.developer.sensorkit.reader.allow) is included and visible in Xcode under the project’s entitlements list. However, when I try to archive and distribute the app, I get the following errors in Xcode: Provisioning profile failed qualification Profile doesn't support SensorKit Reader Access. Provisioning profile failed qualification Profile doesn't include the com.apple.developer.sensorkit.reader.allow entitlement. Even though my provisioning profile includes this entitlement, Xcode still refuses to distribute the app. Here’s what I’ve confirmed so far: The provisioning profile lists com.apple.developer.sensorkit.reader.allow in its entitlements. SensorKit works perfectly in debug and development builds. The issue only occurs when attempting to distribute (Archive → Distribute App). Could this be because my account has only development entitlement for SensorKit and not the distribution entitlement? If so, how can I verify or request the proper distribution entitlement for SensorKit Reader Access? Thank you for any guidance or confirmation from Apple regarding this entitlement behavior.

Hi! We are trying to request the SensorKit entitlement (com.apple.developer.sensorkit.reader.allow) for a research app we’re working on. When we go to Apple Developer → Certificates, Identifiers &amp; Profiles → Identifiers, we see the SensorKit capability listed under "Capability Requests", but: There’s no form or button to submit the request, unlike with other capabilities. We tested this using an Account Holder role, and also tried requesting other capabilities — which do show the form correctly, so this seems to be an issue specific to SensorKit. We’d appreciate any guidance on: Whether this is a known issue with the SensorKit request flow. If there’s an alternative way to request this capability while the form is unavailable. Thanks in advance!

We are a research team conducting a study collecting subject's SensorKit speech data, and we've encountered some questions we couldn't resolve ourselves or by looking up the online SensorKit documentation: Microphone Activation: In general, how is the microphone being turned on to capture a speech session? And how was each session determined to be an independent session? Negative Values: In the speech classification data, there are entries where some of the start and end values are negative (see screenshot below). How should we interpret and handle these values? Is it safe to filter them out? Duplicated sessions: From the same screenshot you can see there are multiple session identifiers linked to the same subject with the same timestamp - what does this represent? Another Negative Values: The same question for speech recognition data's average pause duration, what does the -1 mean and should we remove them as well? (Note that these screenshot got rid of subject IDs for privacy purposes but each screenshot was from one subject.) We greatly appreciate your time and help.

Hi everyone, I’m building a sports performance app for Apple Watch that uses the onboard IMU to analyze swings and impacts in sports like tennis and golf. The goal is to estimate club/racket head speed, ball speed, and shot quality in real time from wrist motion data. With Core Motion, I can currently get deviceMotion updates at ~100 Hz. While this is fine for general movement tracking, the actual ball impact happens much faster — 5–10 ms in tennis and ~0.5 ms in golf. Many of the high-frequency vibration/impact components are missed at 100 Hz, making it hard to directly measure or more accurately estimate certain performance metrics. Questions for Apple / community: 1. Is there a way to access raw accelerometer and gyroscope data at higher sampling rates (e.g., 500–1000 Hz) on Apple Watch? 2. If not, is this due to hardware limitations or an API/software constraint? 3. Are there any research, partner, or beta programs that allow deeper sensor access for sports-science use cases? Even modest increases in IMU sampling could unlock more accurate ball-speed estimates, impact force analysis, and strike-quality detection without needing external sensors — making Apple Watch a best-in-class wearable for precision sports analytics. Happy to share more about the current approach, sample data, and potential use cases if helpful. Thanks, Max

My research group is using watch sensors (accelerometers, gyroscopes) to track wrist motion to detect and measure eating. https://cecas.clemson.edu/ahoover/bite-counter/ We are running an HKWorkoutSession on the watch so that the app can run for an extended period of time (up to 12 hr) and continue to sense and process motion data. Our app is adding to the activity rings, making it look like the user is exercising the entire time our app is running. Is there a method to prevent our app from contributing to the activity ring measures?