A HealthKit sample represents a piece of data associated with a start and end time. If the sample represents data over a duration, the start time must be earlier than the end time. If the sample represents data at a particular instant, the start and end times can be the same.
- iOS 8.0+
- watchOS 2.0+
HKSample class is an abstract class. You should never instantiate a
HKSample object directly. Instead, you always work with one of its concrete subclasses:
HealthKit samples are all immutable: You set the sample’s properties when you create it, and they cannot change.
Like many HealthKit classes, the
HKSample class should not be subclassed. You can extend
HKSample and its subclasses by adding custom metadata keys and values to the metadata dictionary when the object is created.