How to get steps count on hourly basis from HealthKit Swift 4

I need to plot graph for steps taken by user on hourly basis on any specific date. But if the user's steps start today at 3:58 pm and end today at 4:10 pm then I am getting just one HKStatistics object for this period of time. I am not able to break this data into two samples as I need to get steps taken in the 3-4 pm slot and the 4-5 pm slot.

  static func getSteps(date: Date, duration: DateComponents, completion: @escaping ([HKSample]) -> Void) {
        let quantityType : Set = [HKObjectType.quantityType(forIdentifier: HKQuantityTypeIdentifier.stepCount)!]

        let stepsQuantityType = HKQuantityType.quantityType(forIdentifier: .stepCount)!
        let startOfDay = Calendar.current.startOfDay(for: date)
        if let endOfDay = Calendar.current.date(byAdding: duration, to: startOfDay) {
            var interval = DateComponents()
            interval.hour = 1
            let predicate = HKQuery.predicateForSamples(withStart: startOfDay, end: endOfDay, options: .strictStartDate)

            let query = HKSampleQuery.init(sampleType:stepsQuantityType,
                                                 predicate: predicate,
                                                 limit: HKObjectQueryNoLimit,
                                                 sortDescriptors: nil,
                                                 resultsHandler: { (query, results, error) in
                                                    guard let result = results else {

                                                                            return
                                                                        }
                                                   // print("result healthkit",result.description)
                                                    //print("Total count:",)
                                                    completion(result)
            })

            healthStore.execute(query)
        }
    }