# CFCalendarGetTimeRangeOfUnit(_:_:_:_:_:) Returns by reference the start time and duration of a given calendar unit that contains a given absolute time. ``` func CFCalendarGetTimeRangeOfUnit(_ calendar: CFCalendar!, _ unit: CFCalendarUnit, _ at: CFAbsoluteTime, _ startp: UnsafeMutablePointer!, _ tip: UnsafeMutablePointer!) -> Bool ``` ## Parameters `calendar` The calendar to examine. `unit` A calendar unit (for valid values, see [`CFCalendarUnit`](/documentation/CoreFoundation/CFCalendarUnit)). `at` An absolute time. `startp` Upon return, contains the beginning of the calendar unit specified by `unit` that contains the time `at`. `tip` Upon return, contains the duration of the calendar unit specified by `unit` that contains the time `at`. ## Return Value `true` if the values of `startp` and `tip` could be calculated, otherwise `false`. ## Discussion The function may fail if, for example, you try to get the range of a `kCFCalendarUnitWeekday` and specify a time (`at`) that is during a weekend. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)