如何从 swift 中的 HealthKit 获取氧饱和度？

Question

我想要 2 位十进制数的氧饱和度。 但我在除以 100 后得到它。这意味着查询返回HKQuantity ，但我需要百分比的双倍值。 我无法准确解释。 让我们看看我尝试过的代码片段：

public func getOxygenLevel(completion: @escaping (Double?, Error?) -> Void) {

    guard let oxygenQuantityType = HKQuantityType.quantityType(forIdentifier: .oxygenSaturation) else {
        fatalError("*** Unable to get oxygen saturation on this device ***")
    }
    
    HKHealthStore().requestAuthorization(toShare: nil, read: [oxygenQuantityType]) { (success, error) in
        
        guard error == nil, success == true else {
            completion(nil, error)
            return
        }
                
        let predicate = HKQuery.predicateForSamples(withStart: Date.distantPast, end: Date(), options: .strictEndDate)
        let query = HKStatisticsQuery(quantityType: oxygenQuantityType,
                                      quantitySamplePredicate: predicate,
                                      options: .mostRecent) { query, result, error in
            
            DispatchQueue.main.async {
                
                if let err = error {
                    completion(nil, err)
                } else {
                    guard let level = result, let sum = level.mostRecentQuantity() else {
                        completion(nil, error)
                        return
                    }
                    print("Quantity : ", sum)   // It prints 97 % and I need 97 only
                    
                    let measureUnit0 = HKUnit(from: "%")
                    let count0 = sum.doubleValue(for: measureUnit0)
                    print("Count 0 : ", count0)   // It pronts 0.97 and I need 97 only
                    
                    let measureUnit1 = HKUnit.count().unitMultiplied(by: HKUnit.percent())
                    let count1 = sum.doubleValue(for: measureUnit1)
                    print("Count 1 : ", count1)   // It pronts 0.97 and I need 97 only
                    
                    let measureUnit2 = HKUnit.percent()
                    let count2 = sum.doubleValue(for: measureUnit2)
                    print("Count 2 : ", count2)   // It pronts 0.97 and I need 97 only

                    let measureUnit3 = HKUnit.count()
                    let count3 = sum.doubleValue(for: measureUnit3)
                    print("Count 3 : ", count3)   // It pronts 0.97 and I need 97 only

                    completion(count0 * 100.0, nil)
                }
            }
        }
        HKHealthStore().execute(query)
    }
}

Answer 1

文档说Percent measures a value between 0.0 and 1.0 - 所以期望将它乘以 100