如何使用Swift查询Healthkit的平均心率

我需要使用 Swift 2.2查询HKStatistics的平均心率.我从研究中学到了我需要的参数是HKStatisticsOptionDiscreteAverage

我有锻炼课程的代码.如何在以下测量心率的代码中添加该功能,以使用HKStatisticsOptionDiscreteAverage返回锻炼会话的心率平均值？

func createHeartRateStreamingQuery(workoutStartDate: NSDate) -> HKQuery? {
    // adding predicate will not work
    // let predicate = HKQuery.predicateForSamplesWithStartDate(workoutStartDate, endDate: nil, options: HKQueryOptions.None)

    guard let quantityType = HKObjectType.quantityTypeForIdentifier(HKQuantityTypeIdentifierHeartRate) else { return nil }

    let heartRateQuery = HKAnchoredObjectQuery(type: quantityType, predicate: nil, anchor: anchor, limit: Int(HKObjectQueryNoLimit)) { (query, sampleObjects, deletedObjects, newAnchor, error) -> Void in
        guard let newAnchor = newAnchor else {return} 
        self.anchor = newAnchor
        self.updateHeartRate(sampleObjects)
    }

    heartRateQuery.updateHandler = {(query, samples, deleteObjects, newAnchor, error) -> Void in
        self.anchor = newAnchor!
        self.updateHeartRate(samples)
    }
    return heartRateQuery
}

func updateHeartRate(samples: [HKSample]?) {
    guard let heartRateSamples = samples as? [HKQuantitySample] else {return}

    dispatch_async(dispatch_get_main_queue()) {
        guard let sample = heartRateSamples.first else{return}
        let value = sample.quantity.doubleValueForUnit(self.heartRateUnit)
        self.label.setText(String(UInt16(value)))

        // retrieve source from sample
        let name = sample.sourceRevision.source.name
        self.updateDeviceName(name)
        self.animateHeart()
    }
}

func getAVGHeartRate() {

    var typeHeart = HKQuantityType.quantityType(forIdentifier: .heartRate)
    var startDate = Date() - 7 * 24 * 60 * 60 // start date is a week
    var predicate: NSPredicate? = HKQuery.predicateForSamples(withStart: startDate, end: Date(), options: HKQueryOptions.strictEndDate)

    var squery = HKStatisticsQuery(quantityType: typeHeart!, quantitySamplePredicate: predicate, options: .discreteAverage, completionHandler: {(query: HKStatisticsQuery,result: HKStatistics?, error: Error?) -> Void in
        DispatchQueue.main.async(execute: {() -> Void in
            var quantity: HKQuantity? = result?.averageQuantity()
            var beats: Double? = quantity?.doubleValue(for: HKUnit.count().unitDivided(by: HKUnit.minute()))
            print("got: \(String(format: "%.f", beats!))")
        })
        })
    healthStore.execute(squery)
}

这是Swift 3版:)