A piece of data that can be stored inside the HealthKit store.
- iOS 8.0+
- watchOS 2.0+
HKObject class is an abstract class. You should never instantiate a
HKObject object directly. Instead, always work with one of its concrete subclasses:
HealthKit objects are all immutable. With a few exceptions (such as the object’s source revision), the object’s properties are set when the object is first created and they cannot change.