HKQuantityTypeIdentifier watchOS calculate Heart rate while watch is not wrist

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Created Apr ’21

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I am developing an app to calculate the Heart rate using SwiftUI. Code is measuring hear rate accurately. But when I took my watch off form my wrist it still showing the heart rate. I have check the apple heart rate app which stop showing the HR as I took of my watch form wrist.

Code Block swift let healthKitTypes: Set = [        HKObjectType.quantityType(forIdentifier: HKQuantityTypeIdentifier.heartRate)!]
        healthStore.requestAuthorization(toShare: healthKitTypes, read: healthKitTypes) { _, _ in }
        let devicePredicate = HKQuery.predicateForObjects(from: [HKDevice.local()])        
 
let updateHandler: (HKAnchoredObjectQuery, [HKSample]?, [HKDeletedObject]?, HKQueryAnchor?, Error?) -> Void = {            query, samples, deletedObjects, queryAnchor, error in                        
 
       guard let samples = samples as? [HKQuantitySample] else {            return        }                    self.process(samples, type: quantityTypeIdentifier)
        }                
 let query = HKAnchoredObjectQuery(type: HKObjectType.quantityType(forIdentifier: quantityTypeIdentifier)!, predicate: devicePredicate, anchor: nil, limit: HKObjectQueryNoLimit, resultsHandler: updateHandler)                query.updateHandler = updateHandler               
healthStore.execute(query)

How Can I achieve this in my application.

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Answer 1

Claude31 OP

Apr ’21

May have a look here for some preliminary answer:
https://stackoverflow.com/questions/55077716/ios-watchos5-how-to-detect-programmatically-if-apple-watch-was-on-the-wrist-w

May be you could also look at heart rate history and if nothing changed in the last 3 or 4 frames, that could mean the watch is no more on wrist, and thus ignore the measures ?

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