Reading Data

You can query health data from Apple HealthKit and Android Health Connect using the IHealthService interface. Always request read permissions first.

Checking Availability

Before reading or writing, gate on IsAvailable — a whole-store check. On iOS this is always true; on Android it’s true only when Health Connect is installed and the SDK status is OK.

if (!health.IsAvailable)
    return; // Health Connect not installed on Android, etc.

var steps = await health.GetStepCounts(start, end, Interval.Days);

Querying Health Data

public class HealthDashboardViewModel(IHealthService health)
{
    async Task LoadDataAsync()
    {
        // 1. Request permissions (read-only shorthand)
        var result = await health.RequestPermissions(
            DataType.StepCount,
            DataType.HeartRate,
            DataType.Calories,
            DataType.Distance
        );

        // Or request per-metric read/write permissions in a single call
        // await health.RequestPermissions(
        //     (PermissionType.Read, DataType.StepCount),
        //     (PermissionType.Read, DataType.HeartRate),
        //     (PermissionType.Write, DataType.Weight),
        //     (PermissionType.ReadWrite, DataType.BloodPressure)
        // );

        // 2. Check which permissions were granted - the user can grant a subset, so only
        //    query the types that came back true
        var granted = result.Where(x => x.Success).Select(x => x.Type).ToHashSet();
        foreach (var (type, success) in result)
        {
            if (!success)
                Console.WriteLine($"Permission denied for {type}");
        }

        // 3. Query data for the last 24 hours
        var end = DateTimeOffset.Now;
        var start = end.AddDays(-1);

        var steps = (await health.GetStepCounts(start, end, Interval.Days)).Sum(x => x.Value);
        var calories = (await health.GetCalories(start, end, Interval.Days)).Sum(x => x.Value);
        var distance = (await health.GetDistances(start, end, Interval.Days)).Sum(x => x.Value);
        var heartRate = (await health.GetAverageHeartRate(start, end, Interval.Days)).Average(x => x.Value);

        // 4. Blood pressure returns a special result type
        var bp = await health.GetBloodPressure(start, end, Interval.Days);
        if (bp.Any())
        {
            var avgSystolic = bp.Average(x => x.Systolic);
            var avgDiastolic = bp.Average(x => x.Diastolic);
        }

        // 5. Hourly breakdown
        var hourlySteps = await health.GetStepCounts(start, end, Interval.Hours);
        foreach (var bucket in hourlySteps)
        {
            Console.WriteLine($"{bucket.Start:g} - {bucket.End:g}: {bucket.Value:N0} steps");
        }
    }
}

A partial grant is the normal case

Both platforms let the user approve some of what you asked for and refuse the rest, so never treat RequestPermissions as all-or-nothing. On Android, querying a DataType whose permission was not granted throws a HealthConnectException wrapping a SecurityException — it does not return an empty list — so one unapproved type will abort a whole dashboard load if you query unconditionally. Gate each query on the per-DataType result, or wrap them individually.

On iOS, Success is not a reliable signal: HealthKit deliberately does not reveal read denials, so it can report true and still return no samples.

Menstruation / Period Tracking

Menstruation flow is categorical and event-based, so it does not use Interval bucketing. Read the raw records over a date range with GetMenstruationFlow:

await health.RequestPermissions(DataType.MenstruationFlow);

var end = DateTimeOffset.Now;
var start = end.AddMonths(-1);

var records = await health.GetMenstruationFlow(start, end);
foreach (var r in records)
{
    // r.Flow is a MenstrualFlow enum: Unspecified, None, Light, Medium, Heavy
    Console.WriteLine($"{r.Start:d}: {r.Flow}{(r.IsCycleStart ? " (cycle start)" : "")}");
}

Note

The None flow level and the IsCycleStart flag are iOS-only. On Android (Health Connect), None is reported as Unspecified and IsCycleStart is always false.

More Numeric Metrics

Beyond the core activity/body/vitals metrics, the same interval-bucketed pattern works for blood glucose, body temperature, respiratory rate, VO2 max, heart rate variability, lean body mass, active/basal energy, floors climbed, wheelchair pushes, speed, and power:

await health.RequestPermissions(
    DataType.BloodGlucose,
    DataType.RespiratoryRate,
    DataType.Vo2Max,
    DataType.HeartRateVariability,
    DataType.ActiveEnergyBurned,
    DataType.FloorsClimbed
);

var end = DateTimeOffset.Now;
var start = end.AddDays(-1);

var glucose = (await health.GetBloodGlucose(start, end, Interval.Days)).Average(x => x.Value);        // mg/dL
var resp = (await health.GetRespiratoryRate(start, end, Interval.Days)).Average(x => x.Value);         // breaths/min
var vo2 = (await health.GetVo2Max(start, end, Interval.Days)).Average(x => x.Value);                   // mL/kg/min
var hrv = (await health.GetHeartRateVariability(start, end, Interval.Days)).Average(x => x.Value);     // ms
var active = (await health.GetActiveEnergyBurned(start, end, Interval.Days)).Sum(x => x.Value);        // kcal
var floors = (await health.GetFloorsClimbed(start, end, Interval.Days)).Sum(x => x.Value);            // count

Caution

Heart rate variability is reported as SDNN on iOS and RMSSD on Android — both in milliseconds but computed differently, so values are not directly comparable across platforms. Speed maps to walking speed and Power to cycling power on iOS.

Reproductive & Cycle Tracking

Sexual activity, ovulation tests, cervical mucus, and intermenstrual bleeding are event-based (like menstruation flow) — read the raw records over a date range, no Interval:

await health.RequestPermissions(
    DataType.SexualActivity,
    DataType.OvulationTest,
    DataType.CervicalMucus,
    DataType.IntermenstrualBleeding
);

var sexual = await health.GetSexualActivity(start, end);          // .Protection: Unspecified/Protected/Unprotected
var ovulation = await health.GetOvulationTests(start, end);       // .Outcome: Inconclusive/Positive/High/Negative
var mucus = await health.GetCervicalMucus(start, end);            // .Appearance: Dry/Sticky/Creamy/Watery/EggWhite
var spotting = await health.GetIntermenstrualBleeding(start, end);// event-only (no value)

Workouts

await health.RequestPermissions(DataType.Workout);

var workouts = await health.GetWorkouts(start, end);
foreach (var w in workouts)
{
    // w.Workout is a WorkoutType (Running, Cycling, Swimming, …)
    Console.WriteLine($"{w.Workout}: {w.TotalEnergyKilocalories} kcal, {w.TotalDistanceMeters} m");
}

Note

On Android (Health Connect), a workout’s TotalEnergyKilocalories and TotalDistanceMeters are null on read — Health Connect stores energy and distance as separate records from the exercise session.

Nutrition

await health.RequestPermissions(DataType.Nutrition);

var meals = await health.GetNutrition(start, end);
foreach (var m in meals)
    Console.WriteLine($"{m.Meal} {m.Name}: {m.EnergyKilocalories} kcal, {m.ProteinGrams}g protein");

Real-Time Observation

See the dedicated Observing Data page for streaming health data changes via IAsyncEnumerable<HealthResult>.

Best Practices

1. Gate on availability — Check IsAvailable before reading; it returns false for unavailable stores (e.g. Health Connect not installed on Android)
2. Always request permissions first — Call RequestPermissions before reading data
3. Use appropriate intervals — Interval.Days for summaries, Interval.Hours for detailed breakdowns
4. Handle empty results — Check .Any() before calling .Average() to avoid InvalidOperationException
5. Use CancellationToken — Pass cancellation tokens for long-running queries
6. Sum vs Average — Use .Sum() for cumulative metrics (steps, calories, distance, hydration, sleep) and .Average() for point-in-time metrics (heart rate, weight, height, body fat, O2 sat, resting HR)
7. Blood pressure is special — It returns BloodPressureResult (not NumericHealthResult) with separate Systolic and Diastolic values
8. Menstruation is special — It returns MenstruationFlowResult with a categorical MenstrualFlow value and is read via GetMenstruationFlow(start, end) (no Interval)