Case
Calendar.MatchingPolicy.previousTimePreservingSmallerComponents
iOS 8.0+
iPadOS 8.0+
Mac Catalyst 8.0+
macOS 10.10+
tvOS 9.0+
watchOS 2.0+
If there is no matching time before the end of the next instance of the next higher component to the highest specified component in the
DateComponents argument, the algorithm will return the previous existing value of the missing component and preserves the lower components’ values.case previousTimePreservingSmallerComponentsDiscussion
For example, during a daylight saving transition there may be no 2:37am. The result would then be 1:37am, if that does exist.