<!--
{
  "availability" : [
    "iOS: 16.0.0 -",
    "iPadOS: 16.0.0 -",
    "macCatalyst: 16.0.0 -",
    "macOS: 13.0.0 -",
    "tvOS: 16.0.0 -",
    "visionOS: 1.0.0 -"
  ],
  "documentType" : "symbol",
  "framework" : "Metal",
  "identifier" : "/documentation/Metal/MTLIOCompressionContextAppendData(_:_:_:)",
  "metadataVersion" : "0.1.0",
  "role" : "Function",
  "symbol" : {
    "kind" : "Function",
    "modules" : [
      "Metal"
    ],
    "preciseIdentifier" : "c:@F@MTLIOCompressionContextAppendData"
  },
  "title" : "MTLIOCompressionContextAppendData(_:_:_:)"
}
-->

# MTLIOCompressionContextAppendData(_:_:_:)

Adds data to a compression context.

```
func MTLIOCompressionContextAppendData(_ context: MTLIOCompressionContext, _ data: UnsafeRawPointer, _ size: Int)
```

## Parameters

`context`

An [`MTLIOCompressionContext`](/documentation/Metal/MTLIOCompressionContext) instance that you create with the [`MTLIOCreateCompressionContext(_:_:_:)`](/documentation/Metal/MTLIOCreateCompressionContext(_:_:_:)) function.

`data`

A pointer to memory that contains the data the function adds to the compression context.

`size`

The number of bytes the function adds to the compression context from the data pointer.

## Discussion

---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)