Returns, for a given absolute time, the ordinal number of a smaller calendar component (such as a day) within a specified larger calendar component (such as a week).
- iOS 7.0+
- macOS 10.9+
- tvOS 9.0+
- watchOS 2.0+
- Xcode 8.0+
The smaller calendar component.
The larger calendar component.
The absolute time for which the calculation is performed.
The ordinal number of smaller within larger at the time specified by date. Returns
nil if larger is not logically bigger than smaller in the calendar, or the given combination of components does not make sense (or is a computation which is undefined).
The ordinality is in most cases not the same as the decomposed value of the component. Typically return values are 1 and greater. For example, the time 00:45 is in the first hour of the day, and for components
day respectively, the result would be 1. An exception is the week-in-month calculation, which returns 0 for days before the first week in the month containing the date.