Class

HKCorrelationType

A type that identifies samples that group multiple subsamples.

Declaration

class HKCorrelationType : HKSampleType

Overview

The HKCorrelationType class is a concrete subclass of the HKObjectType class. To create a correlation type instance, use the object type’s correlationType(forIdentifier:) conveniance method.

Use correlation types to:

  • Request permission to read or write matching quantity samples.

  • Create and share matching quantity samples.

  • Query for matching quantity samples.

HealthKit provides two correlation types: blood pressure and food.

Using Correlation Types

Like many HealthKit classes, correlation types are not extensible and should not be subclassed.

This class reuses the same instance whenever possible. Letting multiple queries share the same workout type helps reduce the overall memory usage.

Relationships

Inherits From

Conforms To

See Also

Type Objects

class HKCharacteristicType

A type that represents data that does not typically change over time.

class HKQuantityType

A type that identifies samples that store numerical values.

class HKCategoryType

A type that identifies samples that contain a value from a small set of possible values.

class HKActivitySummaryType

A type that identifies activity summary objects.

class HKAudiogramSampleType

A type that identifies samples that contain audiogram data.

Beta
class HKSeriesType

A type that indicates the data stored in a series sample.

class HKObjectType

The abstract superclass for all classes that identify a specific type of data when working with the HealthKit store.

class HKSampleType

An abstract superclass for all classes that identify a specific type of sample when working with the HealthKit store.

class HKClinicalType

A type that identifies samples that contain clinical record data.

class HKWorkoutType

A type that identifies samples that store information about a workout.

Beta Software

This documentation contains preliminary information about an API or technology in development. This information is subject to change, and software implemented according to this documentation should be tested with final operating system software.

Learn more about using Apple's beta software