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# CMSEncoderSetEncapsulatedContentTypeOID(_:_:)

Specifies an object identifier for the encapsulated data of a signed message.

```
func CMSEncoderSetEncapsulatedContentTypeOID(_ cmsEncoder: CMSEncoder, _ eContentTypeOID: CFTypeRef) -> OSStatus
```

## Parameters

`cmsEncoder`

The CMSEncoder reference returned by the `CMSEncoderCreate` function.

`eContentTypeOID`

The object identifier for the encapsulated data in a signed message.

## Return Value

A result code. See [Security Framework Result Codes](/documentation/Security/security-framework-result-codes).

## Discussion

In a signed message, the signed data consists of any type of content (referred to as the *encapsulated content*, because it is encapsulated in the signed data) plus the signature values. You can indicate the content type of the encapsulated data by specifying an object identifier (OID) in the `eContentTypeOID` parameter of this function, in the form of a Core Foundation string—`CFSTR("1.2.840.113549.1.7.1")`, for example.

The default value for the OID (used if this function is not called) is `id-data`. This is the normal encapsulated content type for applications such as S/MIME, which uses it to indicate MIME-encoded content. You can pass any value that is meaningful to your application. Examples of CMS OIDs are listed in <http://www.imc.org/ietf-smime/other-smime-oids.asn>.

If you do call this function, you must call it before the first call to the `CMSEncoderUpdateContent` function.

## See Also

[`CMSDecoderCopyEncapsulatedContentType(_:_:)`](/documentation/Security/CMSDecoderCopyEncapsulatedContentType(_:_:))

Obtains the object identifier for the encapsulated data of a signed message.

[`CMSEncoderUpdateContent(_:_:_:)`](/documentation/Security/CMSEncoderUpdateContent(_:_:_:))

Feeds content bytes into the encoder.

[`CMSEncoderCreate(_:)`](/documentation/Security/CMSEncoderCreate(_:))

Creates a CMSEncoder reference.

[`CMSEncoderCopyEncapsulatedContentType(_:_:)`](/documentation/Security/CMSEncoderCopyEncapsulatedContentType(_:_:))

Obtains the object identifier for the encapsulated data of a signed message.


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