HKQuantity class is a concrete subclass of the
HKSample class. Each quantity sample instance represent a piece of data with a single numeric value. For example, you can use a quantity sample to record the user’s height, the user’s current heart rate, or the number of calories in a hamburger. HealthKit provides a wide range of quantity types, letting you track a number of different health and fitness features.
- iOS 8.0+
- watchOS 2.0+
Quantity samples are immutable: You set the sample’s properties when you create it, and they cannot change.
Like many HealthKit classes, the
HKQuantity class should not be subclassed.
You may extend the
HKQuantity class by adding metadata with custom keys as appropriate for your app. For more information, see