HealthKit：每日心率平均值

Question

我试图从用户的设备获得每天的平均心率。我有下面的代码，在调用时打印“avgHeart”，但没有做任何其他事情。

我正在我自己的手机上进行测试，该手机肯定有心率数据并且已被授权读取心率数据。

func fortnightAvgHeartRate() {
    print("avgHEART")
    let calendar = Calendar.current

    var interval = DateComponents()
    // 14-day time interval
    interval.day = 1

    // Set the anchor date to Monday at 3:00 a.m.
    let anchorDateTMP = calendar.date(byAdding: .day, value: -14, to: Date())!
    let anchorDate = calendar.date(bySettingHour: 0, minute: 0, second: 0, of: anchorDateTMP)!

    guard let quantityType = HKQuantityType.quantityType(forIdentifier: .heartRate) else {
        fatalError("*** Unable to create a step count type ***")
    }

    // Create the query
    let query = HKStatisticsCollectionQuery(quantityType: quantityType,
                                            quantitySamplePredicate: nil,
                                            options: .discreteAverage,
                                            anchorDate: anchorDate,
                                            intervalComponents: interval)

    // Set the results handler
    query.initialResultsHandler = {
        query, results, error in

        guard let statsCollection = results else {
            // Perform proper error handling here
            fatalError("*** An error occurred while calculating the statistics: \(error?.localizedDescription) ***")
        }

        let endDate = Date()

        guard let startDate = calendar.date(byAdding: .day, value: -14, to: endDate) else {
            fatalError("*** Unable to calculate the start date ***")
        }

        // Plot the weekly step counts over the past 3 months
        statsCollection.enumerateStatistics(from: startDate, to: endDate) { [unowned self] statistics, stop in

            if let quantity = statistics.sumQuantity() {
                let date = statistics.startDate
                let value = quantity.doubleValue(for: HKUnit.count())

                let formatter = DateFormatter()
                formatter.dateFormat = "ddMMMyyyy"
                let dateResult = formatter.string(from: date)

                print("HEART")
                self.addToArray(date: dateResult, value: value, number: 5)
            }
        }
    }

    HKHealthStore().execute(query)
}

被调用的函数如下：

var dateArray: [String] = []
var avgHeartRateDataArray: [Double] = []

func addToArray(date: String, value: Double, number: Double) {
    // ...
    if number == 5 {
        avgHeartRateDataArray.append(value)
        print("avgHeartRate: \(avgHeartRateDataArray)")
    }

    if dateArray.contains(date) {
        // Do nothing
    } else {
        dateArray.append(date)
    }

    print("ARRAY1: \(dateArray)")
}

在这方面，print("avgHeartRate: \(avgHeartRateDataArray)")根本没有被召唤。

理想情况下，我希望avgHeartRateData阵列中包含过去14天的平均心率。

Answer 1

主要问题是你要求statistics.sumQuantity()，这个查询总是nil。相反，你应该要求statistics.averageQuantity()。

此外，quantity.doubleValue(for: HKUnit.count())会抛出错误，因为心率不存储在计数中，而是存储在每单位时间内的计数中。要获得每分钟的节拍，请使用HKUnit.count().unitDivided(by: HKUnit.minute())。

这将使您的代码正常工作，但您也应该限制查询所需的日期。不要运行无界查询，然后将结果限制为适合您的日期框架，将谓词设置为仅获取所需的统计信息。

这是一个包含我上面所说的所有内容的例子：

func printFortnightAvgHeartRate() {
    let calendar = Calendar.current

    let heartRateType = HKQuantityType.quantityType(forIdentifier: .heartRate)!

    // Start 14 days back, end with today
    let endDate = Date()
    let startDate = calendar.date(byAdding: .day, value: -14, to: endDate)!

    let predicate = HKQuery.predicateForSamples(withStart: startDate, end: endDate, options: [])

    // Set the anchor to exactly midnight
    let anchorDate = calendar.date(bySettingHour: 0, minute: 0, second: 0, of: Date())!

    // Generate daily statistics
    var interval = DateComponents()
    interval.day = 1

    // Create the query
    let query = HKStatisticsCollectionQuery(quantityType: heartRateType,
                                            quantitySamplePredicate: predicate,
                                            options: .discreteAverage,
                                            anchorDate: anchorDate,
                                            intervalComponents: interval)

    // Set the results handler
    query.initialResultsHandler = { query, results, error in
        guard let statsCollection = results else { return }

        for statistics in statsCollection.statistics() {
            guard let quantity = statistics.averageQuantity() else { continue }

            let beatsPerMinuteUnit = HKUnit.count().unitDivided(by: HKUnit.minute())
            let value = quantity.doubleValue(for: beatsPerMinuteUnit)

            let df = DateFormatter()
            df.dateStyle = .medium
            df.timeStyle = .none
            print("On \(df.string(from: statistics.startDate)) the average heart rate was \(value) beats per minute")
        }
    }

    HKHealthStore().execute(query)
}

作为旁注，在你的addToArray函数中，你似乎使用number参数来区分数据类型。至少使用Int，而不是Double，但理想情况下这应该是enum。