# CMTimeRange A structure that represents a range of time. ## Discussion This document describes the API for creating and manipulating `CMTimeRange` structures. The system represents a `CMTimeRange` as a non-opaque, mutable structure by using two [`CMTime`](/documentation/CoreMedia/CMTime) values that specify the start time and duration of the range. A time range doesn’t include the end time because you calculate it by adding the duration to the start time. ```objc // An expression that evaluates to false. CMTimeRangeContainsTime(range, CMTimeRangeGetEnd(range)) ``` Convert `CMTimeRanges` to and from `CFDictionaries` (see ) using [`CMTimeRangeCopyAsDictionary(_:allocator:)`](/documentation/CoreMedia/CMTimeRangeCopyAsDictionary(_:allocator:)) and [`CMTimeRangeMakeFromDictionary(_:)`](/documentation/CoreMedia/CMTimeRangeMakeFromDictionary(_:)) to use in annotations and various Core Foundation containers. The epoch in a `CMTime` that represents a duration must be `0`, and the value must be nonnegative. The epoch in a `CMTime` that represents a timestamp can be nonzero, but functions (such as [`CMTimeRangeGetUnion(_:otherRange:)`](/documentation/CoreMedia/CMTimeRangeGetUnion(_:otherRange:))) can only perform operations on ranges whose start fields have the same epoch. `CMTimeRanges` can’t span different epochs. For information about additional functions for managing dates and times, see . ## Topics ### Creating Time Ranges [`func CMTimeRangeMake(start: CMTime, duration: CMTime) -> CMTimeRange`](/documentation/CoreMedia/CMTimeRangeMake(start:duration:)) Creates a valid time range with a start time and duration. [`func CMTimeRangeMakeFromDictionary(CFDictionary) -> CMTimeRange`](/documentation/CoreMedia/CMTimeRangeMakeFromDictionary(_:)) Creates a time range from a dictionary representation of its fields. [`func CMTimeRangeFromTimeToTime(start: CMTime, end: CMTime) -> CMTimeRange`](/documentation/CoreMedia/CMTimeRangeFromTimeToTime(start:end:)) Creates a valid time range from a start and end time. ### Comparing Time Ranges [`func CMTimeRangeEqual(CMTimeRange, CMTimeRange) -> Bool`](/documentation/CoreMedia/CMTimeRangeEqual(_:_:)) Returns a Boolean value that indicates whether two time ranges are equal. [`func CMTimeRangeContainsTime(CMTimeRange, time: CMTime) -> Bool`](/documentation/CoreMedia/CMTimeRangeContainsTime(_:time:)) Returns a Boolean value that indicates whether a time range contains a time. [`func CMTimeRangeContainsTimeRange(CMTimeRange, otherRange: CMTimeRange) -> Bool`](/documentation/CoreMedia/CMTimeRangeContainsTimeRange(_:otherRange:)) Returns a Boolean value that indicates whether a time range contains another time range. ### Inspecting Time Ranges [`func CMTIMERANGE_IS_EMPTY(CMTimeRange) -> Bool`](/documentation/CoreMedia/CMTIMERANGE_IS_EMPTY(_:)) Returns a Boolean value that indicates whether a time range has a duration of zero. [`func CMTIMERANGE_IS_INDEFINITE(CMTimeRange) -> Bool`](/documentation/CoreMedia/CMTIMERANGE_IS_INDEFINITE(_:)) Returns a Boolean value that indicates whether a time range is indefinite. [`func CMTIMERANGE_IS_INVALID(CMTimeRange) -> Bool`](/documentation/CoreMedia/CMTIMERANGE_IS_INVALID(_:)) Returns a Boolean value that indicates whether a time range is invalid. [`func CMTIMERANGE_IS_VALID(CMTimeRange) -> Bool`](/documentation/CoreMedia/CMTIMERANGE_IS_VALID(_:)) Returns a Boolean value that indicates whether a time range is valid. [`#define CMTIMERANGE_IS_EMPTY(range)`](/documentation/CoreMedia/CMTIMERANGE_IS_EMPTY) Returns a Boolean value that indicates whether a time range has a duration of zero. [`#define CMTIMERANGE_IS_INDEFINITE(range)`](/documentation/CoreMedia/CMTIMERANGE_IS_INDEFINITE) Returns a Boolean value that indicates whether a time range is indefinite. [`#define CMTIMERANGE_IS_INVALID(range)`](/documentation/CoreMedia/CMTIMERANGE_IS_INVALID) Returns a Boolean value that indicates whether a time range is invalid. [`#define CMTIMERANGE_IS_VALID(range)`](/documentation/CoreMedia/CMTIMERANGE_IS_VALID) Returns a Boolean value that indicates whether a time range is valid. [`func CMTimeRangeGetEnd(CMTimeRange) -> CMTime`](/documentation/CoreMedia/CMTimeRangeGetEnd(_:)) Returns a time value that represents the end of a time range. [`func CMTimeRangeGetIntersection(CMTimeRange, otherRange: CMTimeRange) -> CMTimeRange`](/documentation/CoreMedia/CMTimeRangeGetIntersection(_:otherRange:)) Returns a new time range with the time elements that are common between the input. [`func CMTimeRangeGetUnion(CMTimeRange, otherRange: CMTimeRange) -> CMTimeRange`](/documentation/CoreMedia/CMTimeRangeGetUnion(_:otherRange:)) Returns a new time range with the time elements of the input. ### Utility Functions [`func CMTimeClampToRange(CMTime, range: CMTimeRange) -> CMTime`](/documentation/CoreMedia/CMTimeClampToRange(_:range:)) Returns the nearest time value inside the time range. [`func CMTimeMapDurationFromRangeToRange(CMTime, fromRange: CMTimeRange, toRange: CMTimeRange) -> CMTime`](/documentation/CoreMedia/CMTimeMapDurationFromRangeToRange(_:fromRange:toRange:)) Translates a duration through a mapping from two time ranges. [`func CMTimeMapTimeFromRangeToRange(CMTime, fromRange: CMTimeRange, toRange: CMTimeRange) -> CMTime`](/documentation/CoreMedia/CMTimeMapTimeFromRangeToRange(_:fromRange:toRange:)) Translates a time through a mapping from two time ranges. [`func CMTimeRangeCopyAsDictionary(CMTimeRange, allocator: CFAllocator?) -> CFDictionary?`](/documentation/CoreMedia/CMTimeRangeCopyAsDictionary(_:allocator:)) Returns a dictionary representation of a time range. [`func CMTimeRangeCopyDescription(allocator: CFAllocator?, range: CMTimeRange) -> CFString?`](/documentation/CoreMedia/CMTimeRangeCopyDescription(allocator:range:)) Returns a string with a description of a time range. [`func CMTimeRangeShow(CMTimeRange)`](/documentation/CoreMedia/CMTimeRangeShow(_:)) Prints a description of the time range to standard error. ### Data Types [`struct CMTimeRange`](/documentation/CoreMedia/CMTimeRange) A structure that represents a time range. ### Constants [Dictionary Keys](/documentation/CoreMedia/cmtimerange-dictionary-keys) Keys to use when working with dictionary representations of a time range. [Pre-Specified Time Ranges](/documentation/CoreMedia/pre-specified-time-ranges) Constants that specify zero and invalid time ranges. --- 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)