---
title: "extend(by:)"
framework: coremedia
role: symbol
role_heading: Instance Method
path: "coremedia/cmmutabledatablockbuffer/extend(by:)"
---

# extend(by:)

Extend block buffer by appending a memory block of count bytes.

## Declaration

```swift
mutating func extend(by count: Int)
```

## Parameters

- `count`: Number of bytes to add to the block buffer. Must be greater than 0.