---
title: "readAttributeRmsVoltageSwellPeriod(completionHandler:)"
framework: matter
role: symbol
role_heading: Instance Method
path: "matter/mtrbaseclusterelectricalmeasurement/readattributermsvoltageswellperiod(completionhandler:)"
---

# readAttributeRmsVoltageSwellPeriod(completionHandler:)

## Declaration

```swift
func readAttributeRmsVoltageSwellPeriod(completionHandler: @escaping @Sendable (NSNumber?, (any Error)?) -> Void)
```

```swift
func readAttributeRmsVoltageSwellPeriod() async throws -> NSNumber
```