HealthKit Integration

The iOS app integrates with Apple HealthKit to automatically import running workouts.

Overview

Running Days reads workout data from HealthKit, the centralized health data store on iOS. This allows automatic import of runs from:

Apple Watch workouts
iPhone Workout app
Third-party fitness apps (Strava, Nike Run Club, etc.)

Required Permissions

The app requests read-only access to:

Data Type	Purpose
Workout (Running)	Core workout data
Distance	Run distance
Active Energy	Calories burned
Heart Rate	HR metrics (optional)

Setup

1. Enable HealthKit Capability

In Xcode, add the HealthKit capability to your app target.

2. Request Authorization

swift

import HealthKit

class HealthKitManager {
    let healthStore = HKHealthStore()

    func requestAuthorization() async throws {
        let typesToRead: Set<HKSampleType> = [
            HKObjectType.workoutType(),
            HKQuantityType(.distanceWalkingRunning),
            HKQuantityType(.activeEnergyBurned),
            HKQuantityType(.heartRate)
        ]

        try await healthStore.requestAuthorization(
            toShare: [],
            read: typesToRead
        )
    }
}

3. Query Running Workouts

swift

func fetchRunningWorkouts(since date: Date) async throws -> [HKWorkout] {
    let runningPredicate = HKQuery.predicateForWorkouts(
        with: .running
    )
    let datePredicate = HKQuery.predicateForSamples(
        withStart: date,
        end: Date(),
        options: .strictStartDate
    )
    let compound = NSCompoundPredicate(
        andPredicateWithSubpredicates: [runningPredicate, datePredicate]
    )

    let descriptor = HKSampleQueryDescriptor(
        predicates: [.workout(compound)],
        sortDescriptors: [SortDescriptor(\.startDate, order: .reverse)]
    )

    return try await descriptor.result(for: healthStore)
}

Data Mapping

HealthKit data maps to Running Days as:

HealthKit	Running Days
`workout.startDate`	`startTime`
`workout.endDate`	`endTime`
`workout.duration`	`durationSeconds`
`totalDistance`	`distanceMeters`
`totalEnergyBurned`	`energyBurnedKcal`
`averageHeartRate`	`avgHeartRate`

Background Delivery

For automatic sync when new workouts are recorded:

swift

func enableBackgroundDelivery() async throws {
    try await healthStore.enableBackgroundDelivery(
        for: HKObjectType.workoutType(),
        frequency: .immediate
    )
}

Then handle the background task to sync new workouts.

Privacy Notes

HealthKit data never leaves the device unencrypted
Only running workouts are read (not walks, cycles, etc.)
Users can revoke access anytime in Settings > Privacy > Health
No health data is shared with third parties