如何快速从 HealthKit 中获取氧饱和度？

Posted 2023-03-10

【中文标题】如何快速从 HealthKit 中获取氧饱和度？

【英文标题】：How to get oxygen saturation from HealthKit in swift?

【发布时间】：2021-04-22 13:16:02

【问题描述】：

我想要 2 位十进制数字的氧饱和度。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 sn-p ：

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)
    

【参考方案1】：

文档说Percent measures a value between 0.0 and 1.0 - 所以希望乘以 100

【讨论】：

是的，这就是我最后所做的，但期待我们是否可以直接从 HealthKit 获取

我不这么认为。小心 unitMultiplied(by:) - 这是将单位相乘以获得一种新的单位。这不是乘以值。例如每秒米，是单位长度除以单位时间得到速度单位。 “磅英尺”（扭矩），即单位质量乘以单位长度得到单位力。