Global Variable

HKQuantityTypeIdentifierHeartRateVariabilitySDNN

A quantity sample type that measures the standard deviation of heartbeat intervals.

Declaration

const HKQuantityTypeIdentifier HKQuantityTypeIdentifierHeartRateVariabilitySDNN;

Discussion

These samples use time units (described in HKUnit) and measure discrete values (described in HKStatisticsQuery).

Heart rate variability (HRV) is calculated by measuring the variation between individual heartbeats. While there are multiple ways of computing HRV, HealthKit uses SDNN heart rate variability, which is calculated using the standard deviation of the inter-beat (RR) intervals between normal heartbeats (typically measured in milliseconds).

See Also

Vital Signs

HKQuantityTypeIdentifierHeartRate

A quantity sample type that measures the user’s heart rate.

HKCategoryTypeIdentifierLowHeartRateEvent

A category sample type for low heart rate events.

HKCategoryTypeIdentifierHighHeartRateEvent

A category sample type for high heart rate events.

HKCategoryTypeIdentifierIrregularHeartRhythmEvent

A category sample type for irregular heart rhythm events.

HKQuantityTypeIdentifierRestingHeartRate

A quantity sample type that measures the user’s resting heart rate.

HKQuantityTypeIdentifierWalkingHeartRateAverage

A quantity sample type that measures the user’s heart rate while walking.

HKDataTypeIdentifierHeartbeatSeries

A series sample containing heartbeat data.

Beta
HKQuantityTypeIdentifierOxygenSaturation

A quantity sample type that measures the user’s oxygen saturation.

HKQuantityTypeIdentifierBodyTemperature

A quantity sample type that measures the user’s body temperature.

HKCorrelationTypeIdentifierBloodPressure

Blood pressure correlation types combine a systolic sample and a diastolic sample into a single blood pressure reading.

HKQuantityTypeIdentifierBloodPressureSystolic

A quantity sample type that measures the user’s systolic blood pressure.

HKQuantityTypeIdentifierBloodPressureDiastolic

A quantity sample type that measures the user’s diastolic blood pressure.

HKQuantityTypeIdentifierRespiratoryRate

A quantity sample type that measures the user’s respiratory rate.

HKQuantityTypeIdentifierVO2Max

A quantity sample that measures the maximal oxygen consumption during incremental exercise.