---
title: "luxUnit(with:)"
framework: healthkit
role: symbol
role_heading: Type Method
path: "healthkit/hkunit/luxunit(with:)"
---

# luxUnit(with:)

Returns a HealthKit unit for measuring illuminance, using lux units with the provided prefix.

## Declaration

```swift
class func luxUnit(with prefix: HKMetricPrefix) -> Self
```

## Parameters

- `prefix`: A valid metric prefix value. For the complete list of prefix values, see doc://com.apple.healthkit/documentation/HealthKit/HKMetricPrefix.