---
title: "CMSDecoderUpdateMessage(_:_:_:)"
framework: security
role: symbol
role_heading: Function
path: "security/cmsdecoderupdatemessage(_:_:_:)"
---

# CMSDecoderUpdateMessage(_:_:_:)

Feeds raw bytes of the message to be decoded into the decoder.

## Declaration

```swift
func CMSDecoderUpdateMessage(_ cmsDecoder: CMSDecoder, _ msgBytes: UnsafeRawPointer, _ msgBytesLen: Int) -> OSStatus
```

## Parameters

- `cmsDecoder`: The CMSDecoder reference returned by the CMSDecoderCreate function.
- `msgBytes`: A pointer to the data to be decoded.
- `msgBytesLen`: The length of the data, in bytes.

## Return Value

Return Value A result code. See Security Framework Result Codes. Returns errSecUnknownFormat upon detection of an improperly formatted CMS message.

## Discussion

Discussion This function can be called multiple times. Call the CMSDecoderFinalizeMessage function when you have no more data to decode.

## See Also

### Related Documentation

- [CMSDecoderCreate(_:)](security/cmsdecodercreate(_:).md)