# IOMemoryMap A reference to an existing block of memory in the current process or in a different process. ``` class IOMemoryMap; ``` ## Overview Use an [`IOMemoryMap`](/documentation/DriverKit/IOMemoryMap) object to share an existing block of memory. You don’t create instances of this class directly. Instead, call the [`CreateMapping`](/documentation/DriverKit/IOMemoryDescriptor/CreateMapping) method of [`IOMemoryDescriptor`](/documentation/DriverKit/IOMemoryDescriptor) to create a new memory map object for that descriptor’s contents. Use the methods of this class to get the address and size of the memory block, relative to the current process. An [`IOMemoryMap`](/documentation/DriverKit/IOMemoryMap) object doesn’t own the memory it references, and you must not attempt to free that memory. ## Topics ### Configuring the Memory Map [`init`](/documentation/DriverKit/IOMemoryMap/init) Initializes the memory map object. [`free`](/documentation/DriverKit/IOMemoryMap/free) Performs any final cleanup for the memory map object. ### Getting the Map Attributes [`GetAddress`](/documentation/DriverKit/IOMemoryMap/GetAddress) Returns the address of the memory block. [`GetLength`](/documentation/DriverKit/IOMemoryMap/GetLength) Returns the length of the memory block in bytes. [`GetOffset`](/documentation/DriverKit/IOMemoryMap/GetOffset) Returns the offset from the original start of the memory block. --- Copyright © 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)