---
title: "readAttributeNullableOctetString(withAttributeCache:endpoint:queue:completionHandler:)"
framework: matter
role: symbol
role_heading: Type Method
path: "matter/mtrbaseclustertestcluster/readattributenullableoctetstring(withattributecache:endpoint:queue:completionhandler:)"
---

# readAttributeNullableOctetString(withAttributeCache:endpoint:queue:completionHandler:)

## Declaration

```swift
class func readAttributeNullableOctetString(withAttributeCache attributeCacheContainer: MTRAttributeCacheContainer, endpoint: NSNumber, queue: dispatch_queue_t, completionHandler: @escaping @Sendable (Data?, (any Error)?) -> Void)
```

```swift
class func readAttributeNullableOctetString(withAttributeCache attributeCacheContainer: MTRAttributeCacheContainer, endpoint: NSNumber, queue: dispatch_queue_t) async throws -> Data
```