如何从 WatchKit 正确获取心率？

Question

我试图简单地显示 Apple Watch 上次记录的心率。下面是我正在尝试的，但 updateHeartRate 的完成处理程序中的 results 变量会获取数百万条记录并杀死应用程序（几乎看起来像损坏的数据或做错了什么）：

class InterfaceController: WKInterfaceController {

    @IBOutlet var heartLabel: WKInterfaceLabel!

    let heartRateUnit = HKUnit.countUnit().unitDividedByUnit(HKUnit.minuteUnit())
    let heartRateQuantityType = HKQuantityType.quantityTypeForIdentifier(HKQuantityTypeIdentifierHeartRate)

    override func awakeWithContext(context: AnyObject?) {
        super.awakeWithContext(context)
    }

    override func willActivate() {
        super.willActivate()

        guard HKHealthStore.isHealthDataAvailable() else {
            heartLabel.setText("Not available")
            return
        }

        requestHealthKitAuthorization()
        queryHeartRateSample()
    }

    @IBAction func workoutMenuTapped() {

    }
}

private extension InterfaceController {

    func requestHealthKitAuthorization() {
        guard let heartRateQuantityType = heartRateQuantityType else {
            displayNotAllowed()
            return
        }

        let dataTypes = Set(arrayLiteral: heartRateQuantityType)

        HKHealthStore.sharedInstance?.requestAuthorizationToShareTypes(nil, readTypes: dataTypes) {
            [unowned self] success, error in

            guard success else {
                self.displayNotAllowed()
                return
            }

            self.queryHeartRateSample()
        }
    }

    func displayNotAllowed() {
        heartLabel.setText("Not allowed")
    }

    func queryHeartRateSample() {
        guard let heartRateQuery = getHeartRateQuery() else { return }
        HKHealthStore.sharedInstance?.executeQuery(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.heartLabel.setText(String(UInt16(value)))
        }
    }

    func getHeartRateQuery() -> HKQuery? {
        guard let heartRateQuantityType = heartRateQuantityType else {
            displayNotAllowed()
            return nil
        }

        let heartRateQuery = HKSampleQuery(sampleType: heartRateQuantityType,
            predicate: nil,
            limit: 100,
            sortDescriptors: nil) {
                [unowned self] query, results, error in
                guard let results = results as? [HKQuantitySample] else { return }
                self.updateHeartRate(results)
        }

        return heartRateQuery
    }

}

@available(iOS 8.0, *)
public extension HKHealthStore {

    class var sharedInstance: HKHealthStore? {
        if !HKHealthStore.isHealthDataAvailable() {
            return nil
        }

        struct Singleton {
            static let instance = HKHealthStore()
        }

        return Singleton.instance
    }

}

它确实要求我授予权限，但仍然不会触发更新。我是不是做错了什么？

Answer 1

我更喜欢使用HKAnchoredObjectQuery只搜索添加到HealthKit的新数据，这样可以避免查询所有数据，因此您可以通过以下方式获取最新的心率值权限：

private let healthStore = HKHealthStore()

private let heartRateType = HKQuantityType.quantityTypeForIdentifier(HKQuantityTypeIdentifierHeartRate)!
private let heartRateUnit = HKUnit(fromString: "count/min")

/**
 Start to measure the heart rate.
 */
func startToMeasure() {
    self.healthStore.executeQuery(self.createStreamingQuery()!)
}


/**
Create a query to receive new heart rate data from the HealthKit store.

- returns: The created query
*/
private func createStreamingQuery() -> HKQuery {
    let predicate = HKQuery.predicateForSamplesWithStartDate(NSDate(), endDate: nil, options: .None)

    let query = HKAnchoredObjectQuery(type: heartRateType, predicate: predicate, anchor: nil, limit: Int(HKObjectQueryNoLimit)) {
        (query, samples, deletedObjects, anchor, error) -> Void in
        self.formatSamples(samples)
    }

    query.updateHandler = { (query, samples, deletedObjects, anchor, error) -> Void in
        self.formatSamples(samples)
    }

    return query
}

/**
 Format the samples received from HealthKit.

 - parameter samples: Some samples
 */
private func formatSamples(samples: [HKSample]?) {
    guard let samples = samples as? [HKQuantitySample] else { return }
    guard let quantity = samples.last?.quantity else { return }

    let value = Int(quantity.doubleValueForUnit(heartRateUnit))
    print("HeartRate: \(value)") 
}

上面的代码需要集成到某个类或者UIViewController你有。我在上面的代码中使用了一个谓词来按日期过滤，如果不相关，您可以将其删除。

希望对你有所帮助。