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Authorizing HealthKit

Read Data From HealthKit

Characteristics & Samples

• Biological characteristics:

  Biological characteristics tend to be the kinds of things that don’t change, like your blood type.

  That thing you just can read from HealthKit, can not chenge/write.

• Samples:

  Samples represent things that often do change, like your weight.

  You can read or write. include: HKQuantityType, HKCategoryType etc. subclasses of HKSampleType.

They are all the subclasses of HKObjectType.

Reading Steps

3 main ways to access data from the HealthKit Store:

• Direct method calls. Can be used only to access characteristic data. (for example, blood type).

• Queries.

  8 different types of queries.

  We'll use Statistics collection query (HKStatisticsCollectionQuery) assess step data. Because it can easy creating graphs

• Long-running queries. Can run in the background and update your app whenever changes are made to the HealthKit store.

HKStatisticsCollectionQuery

You can use statistics collection queries only with quantity samples (HKQuantityType)

// Create the query
let query = HKStatisticsCollectionQuery(quantityType: quantityType,
                                        quantitySamplePredicate: nil,
                                        options: .CumulativeSum,
                                        anchorDate: anchorDate,
                                        intervalComponents: interval)
// quantityType: What kind of data do you want query. In this case, is "HKObjectType.quantityType(forIdentifier:HKQuantityTypeIdentifier.stepCount)!"
// quantitySamplePredicate: By this argument you can set the period of data (Which time period data do you want to read). And also you can filter the manually entered data.
// options: We want to calculate the sum of quantities betweent the period time.
// anchorDate: Set the anchorDate. "Because the interval will set to 1 day long, the anchor’s exact date doesn’t matter"
// intervalComponents: The fixed-length time intervals. In our case is 1 day.

Parsing Steps Data

           guard let stepsCollection = results else {
                fatalError("*** An error occurred while calculating the statistics: \(String(describing: error?.localizedDescription)) ***")
            }

            // stepsCollection is HKStatisticsCollection instance
            stepsCollection.enumerateStatistics(from: startDate, to: now, with: { (statistics, stop) in
                if let quantity = statistics.sumQuantity() {
                    let date = statistics.startDate
                    let steps = quantity.doubleValue(for: HKUnit.count())
                    print("\(date.description(with: .current)) : steps = \(Int(steps))")
                }
            })

Source

Use HKSourceQuery can get all sources which have the bundleIdentifier

        let quantityTypesteps = HKQuantityType.quantityType(forIdentifier: .stepCount)
        
        let sourceQuery = HKSourceQuery.init(sampleType: quantityTypesteps!, samplePredicate: nil) { (query, sources, error) in
            guard let dataSources = sources else { return }
            
            for source in dataSources {
                // com.apple.health : The souce(steps) generated by Device
                // com.apple.Health : The souce(steps) entered by user in Health App
                // com.kapps.HealthKitResearch : The souce(steps) generated by third-party Apps
                if source.bundleIdentifier.hasPrefix("com.apple.health") {
                    //  This should give you the iPhone and the Apple watch as the valid sources and ignore the manual entries and all other apps.
                    callBackDataSource.insert(source)
                }
            }
            
            self.dataSourcePredicate = HKQuery.predicateForObjects(from: callBackDataSource)
            done(callBackDataSource)
        }
        HKHealthStore().execute(sourceQuery)