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

# readAttributeUnsupported(completionHandler:)

## Declaration

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

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