---
title: "readAttributeLongOctetString(completion:)"
framework: matter
role: symbol
role_heading: Instance Method
path: "matter/mtrbaseclusterunittesting/readattributelongoctetstring(completion:)"
---

# readAttributeLongOctetString(completion:)

## Declaration

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

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