Modernize HealthKit with async/await

HealthKit provides a central repository for health and fitness data on iPhone and Apple Watch. With the user’s permission, apps communicate with the HealthKit store to access and share this data.

Many HealthKit methods use a completion model. HealthKit gets the new Swift concurrency approach: async/await.

This tutorial require iOS 15.4

Request Authorization from user with HealthKit

First, write the default requirement code

// Prepare HealthStore
let store = HKHealthStore()
// choose data you want in this example we want Caffeine
let samplesType: Set<HKSampleType> = [HKObjectType.quantityType(forIdentifier: .dietaryCaffeine)!]

//Healtkit is only available on iOS and WatchOS
guard HKHealthStore.isHealthDataAvailable() else {
 fatalError()
}

do {
 let authorization = try await healthStore.requestAuthorization(toShare: samplesType, read: samplesType)
} catch {
 fatalError(error.localizedDescription)
}

Your first HealthKit query using the new Swift concurrency async/await

// Prepare HealthStore
let store = HKHealthStore()
// choose data you want in this example we want Caffeine
let samplesType: Set<HKSampleType> = [HKObjectType.quantityType(forIdentifier: .dietaryCaffeine)!]

// Prepare the date one week ago.
let calendar = Calendar.current
var components = calendar.dateComponents([.year, .month, .day], from: Date())
components.day = components.day! - 7
let oneWeekAgo = calendar.date(from: components)

// Prepare the predicate
let queryPredicate = HKQuery.predicateForSamples(withStart: oneWeekAgo, end: .now, options: .strictEndDate)
// Prepare descriptor that represente query
let queryDescriptor = HKSampleQueryDescriptor(
 predicates: [
 .quantitySample(type: HKSampleType.quantityType(forIdentifier: .dietaryCaffeine)!, predicate: query),
 ], 
 sortDescriptors: []
)

// We can now request the store
let results = try await queryDescriptor.result(for: healthStore)

// We can now play with the result, for example
results.map(\.quantity).map { $0.doubleValue(for: .gram()) }