---
title: "CFTimeZoneIsDaylightSavingTime(_:_:)"
framework: corefoundation
role: symbol
role_heading: Function
path: "corefoundation/cftimezoneisdaylightsavingtime(_:_:)"
---

# CFTimeZoneIsDaylightSavingTime(_:_:)

Returns whether or not a time zone is in daylight savings time at a specified date.

## Declaration

```swift
func CFTimeZoneIsDaylightSavingTime(_ tz: CFTimeZone!, _ at: CFAbsoluteTime) -> Bool
```

## Parameters

- `tz`: The time zone to analyze.
- `at`: The date in tz to test for daylight savings.

## Return Value

Return Value true if tz is in daylight savings time at at, otherwise false.

## See Also

### Getting Daylight Savings Time Information

- [CFTimeZoneGetDaylightSavingTimeOffset(_:_:)](corefoundation/cftimezonegetdaylightsavingtimeoffset(_:_:).md)
- [CFTimeZoneGetNextDaylightSavingTimeTransition(_:_:)](corefoundation/cftimezonegetnextdaylightsavingtimetransition(_:_:).md)