Query real time heart rate variability and heart rate values - swift

Question

I'm trying to read out real time heart rate + heart rate variability data from the apple watch.
I am able to read the heartRate value but don't know how to implement the reading of the HRV. I it possible to have them read out simultaneously ?
class HealthKitManager {
private var healthStore = HKHealthStore()
private var heartRateQuantity = HKUnit(from: "count/min")
private var heartRateVariability = HKUnit(from: "count/min")
private var activeQueries = [HKQuery]()
#Published var heartRateValues = HeartRateValues()
func autorizeHealthKit() {
let heartRate = HKObjectType.quantityType(forIdentifier: .heartRate)!
let heartRateVariability = HKObjectType.quantityType(forIdentifier: .heartRateVariabilitySDNN)!
let HKreadTypes: Set = [heartRate, heartRateVariability]
healthStore.requestAuthorization(toShare: nil, read: HKreadTypes) { (success, error) in
if let error = error {
print("Error requesting health kit authorization: \(error)")
}
}
}
func fetchHeartRateData(quantityTypeIdentifier: HKQuantityTypeIdentifier ) {
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)
activeQueries.append(query)
}
private func process(_ samples: [HKQuantitySample], type: HKQuantityTypeIdentifier) {
for sample in samples {
if type == .heartRate {
DispatchQueue.main.async {
self.heartRateValues.heartRate = sample.quantity.doubleValue(for: self.heartRateQuantity)
}
}
// Not Sure about this part and readings show 0.0
else if type == .heartRateVariabilitySDNN {
DispatchQueue.main.async {
self.heartRateValues.heartRateVariability = sample.quantity.doubleValue(for: self.heartRateVariability)
}
}
}
}
func stopFetchingHeartRateData() {
activeQueries.forEach { healthStore.stop($0) }
activeQueries.removeAll()
DispatchQueue.main.async {
self.heartRateValues.heartRate = 0.0
self.heartRateValues.heartRateVariability = 0.0
}
}
}
A comparable question was asked here but it didn't receive an answer:
Get Apple watch heartRateVariabilitySDNN realtime?

Answer 1

I managed to get the hrs reading as well, just added:
private func process(_ samples: [HKQuantitySample], type: HKQuantityTypeIdentifier) {
for sample in samples {
if type == .heartRate {
DispatchQueue.main.async {
self.heartRateValues.heartRate = sample.quantity.doubleValue(for: self.heartRateQuantity)
}
} else if type == .heartRateVariabilitySDNN {
DispatchQueue.main.async {
self.heartRateValues.heartRateVariability = sample.quantity.doubleValue(for: self.heartRateVariabilityQuantity)
}
}
}
}
And then call the class with:
fetchHeartRateData(quantityTypeIdentifier: .heartRate)
fetchHeartRateData(quantityTypeIdentifier: .heartRateVariabilitySDNN)
Problem remains the HRV value get's read once, and doesn't change over time. Any ideas ?