---
title: "withUnsafeMutableBlockRegions(_:)"
framework: coremedia
role: symbol
role_heading: Instance Method
path: "coremedia/cmmutabledatablockbuffer/withunsafemutableblockregions(_:)"
---

# withUnsafeMutableBlockRegions(_:)

Access the potentially non-contiguous memory region referenced by this block buffer.

## Declaration

```swift
mutating func withUnsafeMutableBlockRegions<R>(_ body: ([CMMutableDataBlockBuffer.BlockRegion]) throws -> sending R) rethrows -> sending R
```