---
title: UnitFrequency
framework: foundation
role: symbol
role_heading: Class
path: foundation/unitfrequency
---

# UnitFrequency

A unit of measure for frequency.

## Declaration

```swift
class UnitFrequency
```

## Overview

Overview You typically use instances of UnitFrequency to represent specific quantities of frequency using the NSMeasurement class. Frequency Frequency is a quantity of occurrences for a repeating event over time. The SI unit for frequency is the hertz (Hz), which is a derived as one occurrence per second (1 Hz = 1 / 1s). The UnitFrequency class defines its baseUnit() as hertz, and provides the following units, which are initialized using UnitConverterLinear converters with the specified coefficients:  |  |  |   |  |  |   |  |  |   |  |  |   |  |  |   |  |  |   |  |  |   |  |  |   |  |  |

## Topics

### Accessing the Base Unit

- [baseUnit()](foundation/dimension/baseunit().md)

### Accessing Predefined Units

- [terahertz](foundation/unitfrequency/terahertz.md)
- [gigahertz](foundation/unitfrequency/gigahertz.md)
- [megahertz](foundation/unitfrequency/megahertz.md)
- [kilohertz](foundation/unitfrequency/kilohertz.md)
- [hertz](foundation/unitfrequency/hertz.md)
- [millihertz](foundation/unitfrequency/millihertz.md)
- [microhertz](foundation/unitfrequency/microhertz.md)
- [nanohertz](foundation/unitfrequency/nanohertz.md)
- [framesPerSecond](foundation/unitfrequency/framespersecond.md)

## Relationships

### Inherits From

- [Dimension](foundation/dimension.md)

### Conforms To

- [CVarArg](swift/cvararg.md)
- [CustomDebugStringConvertible](swift/customdebugstringconvertible.md)
- [CustomStringConvertible](swift/customstringconvertible.md)
- [Equatable](swift/equatable.md)
- [Hashable](swift/hashable.md)
- [NSCoding](foundation/nscoding.md)
- [NSCopying](foundation/nscopying.md)
- [NSObjectProtocol](objectivec/nsobjectprotocol.md)
- [NSSecureCoding](foundation/nssecurecoding.md)
- [Sendable](swift/sendable.md)
- [SendableMetatype](swift/sendablemetatype.md)

## See Also

### Time and Motion

- [UnitAcceleration](foundation/unitacceleration.md)
- [UnitDuration](foundation/unitduration.md)
- [UnitSpeed](foundation/unitspeed.md)