---
title: "readAttributeNullableOctetString(completionHandler:)"
framework: matter
role: symbol
role_heading: Instance Method
path: "matter/mtrbaseclustertestcluster/readattributenullableoctetstring(completionhandler:)"
---

# readAttributeNullableOctetString(completionHandler:)

## Declaration

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

```swift
func readAttributeNullableOctetString() async throws -> Data
```