---
title: "mapMemory(_:atOffset:size:completionHandler:)"
framework: virtualization
role: symbol
role_heading: Instance Method
path: "virtualization/vzvirtiosharedmemoryregion/mapmemory(_:atoffset:size:completionhandler:)"
---

# mapMemory(_:atOffset:size:completionHandler:)

Maps a chunk of host memory into the shared memory region.

## Declaration

```swift
func mapMemory(_ memory: UnsafeMutableRawPointer, atOffset offset: UInt64, size: UInt64, completionHandler: @escaping @Sendable ((any Error)?) -> Void)
```

```swift
func mapMemory(_ memory: UnsafeMutableRawPointer, atOffset offset: UInt64, size: UInt64) async throws
```

## Parameters

- `memory`: A pointer to host memory to map into the shared memory region.
- `offset`: The offset from the start of the shared memory region where the memory should map to.
- `size`: The size of the memory to map into the shared memory region.
- `completionHandler`: A block the framework calls after successfully mapping the memory, or on an error. The error parameter passed to the block is nil if the map operation is successful. The framework invokes the block on doc://com.apple.virtualization/documentation/Virtualization/VZCustomVirtioDevice/deviceQueue.