---
title: "CFTimeZoneGetDaylightSavingTimeOffset(_:_:)"
framework: corefoundation
role: symbol
role_heading: Function
path: "corefoundation/cftimezonegetdaylightsavingtimeoffset(_:_:)"
---

# CFTimeZoneGetDaylightSavingTimeOffset(_:_:)

Returns the daylight saving time offset for a time zone at a given time.

## Declaration

```swift
func CFTimeZoneGetDaylightSavingTimeOffset(_ tz: CFTimeZone!, _ at: CFAbsoluteTime) -> CFTimeInterval
```

## Parameters

- `tz`: The time zone to analyze.
- `at`: The time in tz to test for daylight saving time offset.

## Return Value

Return Value The daylight saving time offset for tz at at.

## See Also

### Getting Daylight Savings Time Information

- [CFTimeZoneIsDaylightSavingTime(_:_:)](corefoundation/cftimezoneisdaylightsavingtime(_:_:).md)
- [CFTimeZoneGetNextDaylightSavingTimeTransition(_:_:)](corefoundation/cftimezonegetnextdaylightsavingtimetransition(_:_:).md)