# CFTimeZone ``` class CFTimeZone ``` ## Overview CFTimeZone defines the behavior of time zone objects. Time zone objects represent geopolitical regions. Consequently, these objects have names for these regions. Time zone objects also represent a temporal offset, either plus or minus, from Greenwich Mean Time (GMT) and an abbreviation (such as PST for Pacific Standard Time). CFTimeZone provides several functions to create time zone objects: [`CFTimeZoneCreateWithName(_:_:_:)`](/documentation/CoreFoundation/CFTimeZoneCreateWithName(_:_:_:)) and [`CFTimeZoneCreateWithTimeIntervalFromGMT(_:_:)`](/documentation/CoreFoundation/CFTimeZoneCreateWithTimeIntervalFromGMT(_:_:)). CFTimeZone also permits you to set the default time zone within your application using the [`CFTimeZoneSetDefault(_:)`](/documentation/CoreFoundation/CFTimeZoneSetDefault(_:)) function. You can access this default time zone at any time with the [`CFTimeZoneCopyDefault()`](/documentation/CoreFoundation/CFTimeZoneCopyDefault()) function. CFTimeZone is “toll-free bridged” with its Cocoa Foundation counterpart, . This means that the Core Foundation type is interchangeable in function or method calls with the bridged Foundation object. Therefore, in a method where you see an `NSTimeZone *` parameter, you can pass in a `CFTimeZoneRef`, and in a function where you see a `CFTimeZoneRef` parameter, you can pass in an NSTimeZone instance. This fact also applies to concrete subclasses of NSTimeZone. See [Toll-Free Bridged Types](https://developer.apple.com/library/archive/documentation/CoreFoundation/Conceptual/CFDesignConcepts/Articles/tollFreeBridgedTypes.html#//apple_ref/doc/uid/TP40010677) for more information on toll-free bridging. ## Topics ### Creating a Time Zone [`CFTimeZoneCreateWithName(_:_:_:)`](/documentation/CoreFoundation/CFTimeZoneCreateWithName(_:_:_:)) Returns the time zone object identified by a given name or abbreviation. [`CFTimeZoneCreateWithTimeIntervalFromGMT(_:_:)`](/documentation/CoreFoundation/CFTimeZoneCreateWithTimeIntervalFromGMT(_:_:)) Returns a time zone object for the specified time interval offset from Greenwich Mean Time (GMT). [`CFTimeZoneCreate(_:_:_:)`](/documentation/CoreFoundation/CFTimeZoneCreate(_:_:_:)) Creates a time zone with a given name and data. ### System and Default Time Zones and Information [`CFTimeZoneCopyAbbreviationDictionary()`](/documentation/CoreFoundation/CFTimeZoneCopyAbbreviationDictionary()) Returns a dictionary holding the mappings of time zone abbreviations to time zone names. [`CFTimeZoneCopyAbbreviation(_:_:)`](/documentation/CoreFoundation/CFTimeZoneCopyAbbreviation(_:_:)) Returns the abbreviation of a time zone at a specified date. [`CFTimeZoneCopyDefault()`](/documentation/CoreFoundation/CFTimeZoneCopyDefault()) Returns the default time zone set for your application. [`CFTimeZoneCopySystem()`](/documentation/CoreFoundation/CFTimeZoneCopySystem()) Returns the time zone currently used by the system. [`CFTimeZoneSetDefault(_:)`](/documentation/CoreFoundation/CFTimeZoneSetDefault(_:)) Sets the default time zone for your application the given time zone. [`CFTimeZoneCopyKnownNames()`](/documentation/CoreFoundation/CFTimeZoneCopyKnownNames()) Returns an array of strings containing the names of all the time zones known to the system. [`CFTimeZoneResetSystem()`](/documentation/CoreFoundation/CFTimeZoneResetSystem()) Clears the previously determined system time zone, if any. [`CFTimeZoneSetAbbreviationDictionary(_:)`](/documentation/CoreFoundation/CFTimeZoneSetAbbreviationDictionary(_:)) Sets the abbreviation dictionary to a given dictionary. ### Getting Information About Time Zones [`CFTimeZoneGetName(_:)`](/documentation/CoreFoundation/CFTimeZoneGetName(_:)) Returns the geopolitical region name that identifies a given time zone. [`CFTimeZoneCopyLocalizedName(_:_:_:)`](/documentation/CoreFoundation/CFTimeZoneCopyLocalizedName(_:_:_:)) Returns the localized name of a given time zone. [`CFTimeZoneGetSecondsFromGMT(_:_:)`](/documentation/CoreFoundation/CFTimeZoneGetSecondsFromGMT(_:_:)) Returns the difference in seconds between the receiver and Greenwich Mean Time (GMT) at the specified date. [`CFTimeZoneGetData(_:)`](/documentation/CoreFoundation/CFTimeZoneGetData(_:)) Returns the data that stores the information used by a time zone. ### Getting Daylight Savings Time Information [`CFTimeZoneIsDaylightSavingTime(_:_:)`](/documentation/CoreFoundation/CFTimeZoneIsDaylightSavingTime(_:_:)) Returns whether or not a time zone is in daylight savings time at a specified date. [`CFTimeZoneGetDaylightSavingTimeOffset(_:_:)`](/documentation/CoreFoundation/CFTimeZoneGetDaylightSavingTimeOffset(_:_:)) Returns the daylight saving time offset for a time zone at a given time. [`CFTimeZoneGetNextDaylightSavingTimeTransition(_:_:)`](/documentation/CoreFoundation/CFTimeZoneGetNextDaylightSavingTimeTransition(_:_:)) Returns the time in a given time zone of the next daylight saving time transition after a given time. ### Getting the CFTimeZone Type ID [`CFTimeZoneGetTypeID()`](/documentation/CoreFoundation/CFTimeZoneGetTypeID()) Returns the type identifier for the CFTimeZone opaque type. ### Data Types [`CFTimeZoneNameStyle`](/documentation/CoreFoundation/CFTimeZoneNameStyle) Index type for constants used to specify styles of time zone names. ### Constants [Notification Name](/documentation/CoreFoundation/notification-name) Name of the notification posted when the time zone changes. [Time Zone Name Styles](/documentation/CoreFoundation/time_zone_name_styles) Constants to specify styles for time zone names. ## See Also [Date and Time Programming Guide for Core Foundation](https://developer.apple.com/library/archive/documentation/CoreFoundation/Conceptual/CFDatesAndTimes/CFDatesAndTimes.html#//apple_ref/doc/uid/10000125i) --- 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)