---
title: "readAttributeRmsVoltageSwellPeriodPhaseB(completion:)"
framework: matter
role: symbol
role_heading: Instance Method
path: "matter/mtrbaseclusterelectricalmeasurement/readattributermsvoltageswellperiodphaseb(completion:)"
---

# readAttributeRmsVoltageSwellPeriodPhaseB(completion:)

## Declaration

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

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