How to save an array of HKQuantitySamples (heart rate) to a workout

import UIKit
import HealthKit

class ViewController: UIViewController {
@IBOutlet weak var heartRateLabel: UILabel!
@IBOutlet weak var timeStampLabel: UILabel!

var hkStore: HKHealthStore?
let heartRateUnit: HKUnit = HKUnit.count().unitDivided(by: .minute())
var healthStore: HKHealthStore?
override func viewDidLoad() {
    super.viewDidLoad()
    healthStore = HKHealthStore()
    let sampleTypes = HKSampleType.quantityType(forIdentifier: HKQuantityTypeIdentifier.heartRate)!

    healthStore?.requestAuthorization(toShare: [sampleTypes], read: [sampleTypes], completion: { (success, error) in
        if (error != nil) {
            print(error!.localizedDescription)
        }
    })

    getSamples()
}
func getSamples() {
    let heartrate = HKQuantityType.quantityType(forIdentifier: HKQuantityTypeIdentifier.heartRate)
    let sort = [
        NSSortDescriptor(key: HKSampleSortIdentifierStartDate, ascending: false)
    ]
    let sampleQuery = HKSampleQuery(sampleType: heartrate!, predicate: nil, limit: 1, sortDescriptors: sort, resultsHandler: { [unowned self] (query, results, error) in
        if let results = results as? [HKQuantitySample]
        {
            let sample = results[0] as HKQuantitySample
            let value = sample.quantity.doubleValue(for: self.heartRateUnit)
            let rate = results[0]
            print(value, rate)
            self.updateHeartRate(samples: results)
        }
    })
    healthStore?.execute(sampleQuery)
}

func updateHeartRate(samples: [HKSample]?) {
    guard let heartRateSamples = samples as? [HKQuantitySample] else {return}
    DispatchQueue.main.async {
        guard let sample = heartRateSamples.first else{return}
        let value = sample.quantity.doubleValue(for: self.heartRateUnit)
        self.heartRateLabel.text = String(UInt16(value))
        let date = sample.startDate
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "yyyy-MM-dd hh:mm:ss"
        self.timeStampLabel.text = dateFormatter.string(from: date)
     }
 }
}