HKDocument class is a concrete subclass of the
HKSample class, used when creating queries for documents.
- iOS 10.0+
- Mac Catalyst 13.0+
- watchOS 3.0+
Like many HealthKit classes, document types are not extensible and should not be subclassed.
Additionally, this class reuses the same instance whenever possible. Letting multiple queries share the same document type helps reduce the overall memory usage.