Wrapper for HKHealthStore written in RxSwift to return steps count, distance(walking & running) & active energy burned.

HealthKitManager.swift

import Foundation
import HealthKit
import RxSwift

class HealthKitManager {
  
  private let healthStore = HKHealthStore()
  
  func requestPermission() -> Observable<Bool> {
    return .create { [weak self] (observer) -> Disposable in
      let healthKitTypes: Set = [ HKObjectType.quantityType(forIdentifier: .stepCount)!, HKObjectType.quantityType(forIdentifier: .distanceWalkingRunning)! ]
      self?.healthStore.requestAuthorization(toShare: healthKitTypes, read: healthKitTypes, completion: { (success, error) in
        if let error = error {
          observer.onError(error)
        }
        observer.onNext(success)
        observer.onCompleted()
      })
      return Disposables.create()
    }
  }
  
  func getSteps(for date: Date, interval: DateComponents) -> Observable<Double> {
    return .create { [weak self] (observer) -> Disposable in
      let stepsCount = HKQuantityType.quantityType(forIdentifier: .stepCount)!
      let query = HKStatisticsCollectionQuery(quantityType: stepsCount, quantitySamplePredicate: nil, options: [.cumulativeSum], anchorDate: date, intervalComponents: interval)
      query.initialResultsHandler = { _, result, error in
        if let error = error {
          observer.onError(error)
        }
        if let result = result {
          var resultCount = 0.0
          result.enumerateStatistics(from: date, to: Date()) { statistics, _ in
            if let sum = statistics.sumQuantity() {
              // Get steps (they are of double type)
              resultCount = sum.doubleValue(for: HKUnit.count())
            } // end if
            observer.onNext(resultCount)
          }
        }
        observer.onCompleted()
      }
      self?.healthStore.execute(query)
      return Disposables.create()
    }
  }
  
  func getDistance(for date: Date, interval: DateComponents) -> Observable<Double> {
    return .create { [weak self] (observer) -> Disposable in
      let distanceWalkingRunning = HKQuantityType.quantityType(forIdentifier: .distanceWalkingRunning)!
      let query = HKStatisticsCollectionQuery(quantityType: distanceWalkingRunning, quantitySamplePredicate: nil, options: [.cumulativeSum], anchorDate: date, intervalComponents: interval)
      query.initialResultsHandler = { _, result, error in
        if let error = error {
          observer.onError(error)
        }
        if let result = result {
          var resultCount = 0.0
          result.enumerateStatistics(from: date, to: Date()) { statistics, _ in
            if let sum = statistics.sumQuantity() {
              // Get steps (they are of double type)
              resultCount = sum.doubleValue(for: HKUnit.meter())
            } // end if
          }
          observer.onNext(resultCount)
        }
        observer.onCompleted()
      }
      self?.healthStore.execute(query)
      return Disposables.create()
    }
  }
  
  func getCaloriesCount(for date: Date, interval: DateComponents) -> Observable<Double> {
    return .create { [weak self] (observer) -> Disposable in
      let activeEnergyBurned = HKQuantityType.quantityType(forIdentifier: .activeEnergyBurned)!
      let query = HKStatisticsCollectionQuery(quantityType: activeEnergyBurned, quantitySamplePredicate: nil, options: [.cumulativeSum], anchorDate: date, intervalComponents: interval)
      query.initialResultsHandler = { _, result, error in
        if let error = error {
          observer.onError(error)
        }
        if let result = result {
          var resultCount = 0.0
          result.enumerateStatistics(from: date, to: Date()) { statistics, _ in
            if let sum = statistics.sumQuantity() {
              // Get steps (they are of double type)
              resultCount = sum.doubleValue(for: HKUnit.kilocalorie())
            } // end if
            observer.onNext(resultCount)
          }
        }
        observer.onCompleted()
      }
      self?.healthStore.execute(query)
      return Disposables.create()
    }
  }
}