---
title: "init(unsafeBlockBuffer:)"
framework: coremedia
role: symbol
role_heading: Initializer
path: "coremedia/cmmutabledatablockbuffer/init(unsafeblockbuffer:)"
---

# init(unsafeBlockBuffer:)

Creates a mutable block buffer from an existing block buffer.

## Declaration

```swift
init(unsafeBlockBuffer: sending CMBlockBuffer)
```

## Parameters

- `unsafeBlockBuffer`: The doc://com.apple.coremedia/documentation/CoreMedia/CMBlockBuffer which will be subsumed by the new instance.

## Discussion

Discussion This init will make sure that all memory referenced by unsafeBlockBuffer is allocated by calling assureBlockMemory().