Apple HealthKit葡萄糖水平读数显示转换错误

Question

I am facing below error for the code. below code is for Apple health kit reading glucose levels from HealthApp.

func updateGluco(){

let sampleType = HKSampleType.quantityTypeForIdentifier(HKQuantityTypeIdentifierBloodGlucose)
self.healthManager?.readMostRecentSample(sampleType, completion: {(mostRecentGluco, error) -> Void in

    if (error != nil){
        println("Error reading blood glucose from HealthKit store: \(error.localizedDescription)")
        return;
    }

    var glucoLocalizedString = self.kUnknownString;
    self.gluco = mostRecentGluco as? HKQuantitySample
    println("\(self.gluco?.quantity.doubleValueForUnit(HKUnit.moleUnitWithMolarMass(HKUnitMolarMassBloodGlucose)))")
    self.gluco?.quantity.doubleValueForUnit(HKUnit.moleUnitWithMolarMass(HKUnitMolarMassBloodGlucose))
    if let mmol = self.gluco?.quantity.doubleValueForUnit(HKUnit.moleUnitWithMolarMass(HKUnitMolarMassBloodGlucose)) {
        glucoLocalizedString = "\(mmol)"
    } else {
        println("error reading gluco data!")
    }
    dispatch_async(dispatch_get_main_queue(), {() -> Void in
    self.glucoLabel.text = glucoLocalizedString})
})

}

'NSInvalidArgumentException', reason: 'Attempt to convert incompatible units: mg/dL, mol<180.1558800000541>'

at this line self.gluco?.quantity.doubleValueForUnit(HKUnit.moleUnitWithMolarMass(HKUnitMolarMassBloodGlucose))

Answer 1

The conversion you are attempting to make is invalid. You cannot convert a mass / volume ( mg/dL ) quantity to just a molar mass ( mol ). Try converting mg/dL -> mmol/L (millimoles per liter), which is a valid and common conversion for blood glucose measurements.

let mmol = HKUnit.moleUnit(with: .milli, molarMass: HKUnitMolarMassBloodGlucose)
let mmolL = mmol.unitDivided(by: HKUnit.liter())