---
title: CMAttachment
framework: coremedia
role: collectionGroup
role_heading: API Collection
path: coremedia/cmattachment-api
---

# CMAttachment

Add supporting metadata to sample buffers.

## Overview

Overview An attachment bearer is a Core Foundation type object that supports the suite of key, value, and mode attachment APIs. You can attach any Core Foundation object to an attachment bearer to store additional information.

## Topics

### Processing Attachments

- [CMGetAttachment(_:key:attachmentModeOut:)](coremedia/cmgetattachment(_:key:attachmentmodeout:).md)
- [CMCopyDictionaryOfAttachments(allocator:target:attachmentMode:)](coremedia/cmcopydictionaryofattachments(allocator:target:attachmentmode:).md)
- [CMSetAttachment(_:key:value:attachmentMode:)](coremedia/cmsetattachment(_:key:value:attachmentmode:).md)
- [CMSetAttachments(_:attachments:attachmentMode:)](coremedia/cmsetattachments(_:attachments:attachmentmode:).md)
- [CMRemoveAttachment(_:key:)](coremedia/cmremoveattachment(_:key:).md)
- [CMRemoveAllAttachments(_:)](coremedia/cmremoveallattachments(_:).md)
- [CMPropagateAttachments(_:destination:)](coremedia/cmpropagateattachments(_:destination:).md)

### Data Types

- [CMAttachmentBearerProtocol](coremedia/cmattachmentbearerprotocol.md)
- [CMAttachmentBearer](coremedia/cmattachmentbearer.md)
- [CMAttachmentMode](coremedia/cmattachmentmode.md)

### Constants

- [kCMAttachmentMode_ShouldNotPropagate](coremedia/kcmattachmentmode_shouldnotpropagate.md)
- [kCMAttachmentMode_ShouldPropagate](coremedia/kcmattachmentmode_shouldpropagate.md)
- [kCMSampleAttachmentKey_HEVCTemporalLevelInfo](coremedia/kcmsampleattachmentkey_hevctemporallevelinfo.md)
- [kCMSampleAttachmentKey_HEVCTemporalSubLayerAccess](coremedia/kcmsampleattachmentkey_hevctemporalsublayeraccess.md)
- [kCMSampleAttachmentKey_HEVCStepwiseTemporalSubLayerAccess](coremedia/kcmsampleattachmentkey_hevcstepwisetemporalsublayeraccess.md)
- [kCMSampleAttachmentKey_HEVCSyncSampleNALUnitType](coremedia/kcmsampleattachmentkey_hevcsyncsamplenalunittype.md)
- [kCMSampleAttachmentKey_CryptorSubsampleAuxiliaryData](coremedia/kcmsampleattachmentkey_cryptorsubsampleauxiliarydata.md)
- [kCMSampleAttachmentKey_AudioIndependentSampleDecoderRefreshCount](coremedia/kcmsampleattachmentkey_audioindependentsampledecoderrefreshcount.md)
- [kCMSampleBufferAttachmentKey_CameraIntrinsicMatrix](coremedia/kcmsamplebufferattachmentkey_cameraintrinsicmatrix.md)

## See Also

### Sample Processing

- [CMSampleBuffer](coremedia/cmsamplebuffer-api.md)
- [CMBlockBuffer](coremedia/cmblockbuffer-api.md)
- [CMTaggedBufferGroup](coremedia/cmtaggedbuffergroup.md)
- [CMFormatDescription](coremedia/cmformatdescription-api.md)
- [CMTaggedBuffer](coremedia/cmtaggedbuffer.md)
- [CMMutableDataBlockBuffer](coremedia/cmmutabledatablockbuffer.md)
- [CMReadOnlyDataBlockBuffer](coremedia/cmreadonlydatablockbuffer.md)
- [CMReadySampleBuffer](coremedia/cmreadysamplebuffer.md)
- [CMSampleDataReference](coremedia/cmsampledatareference.md)
- [CMTaggedDynamicBuffer](coremedia/cmtaggeddynamicbuffer.md)