# copyMemory(from:byteCount:) Copies the specified number of bytes from the given raw pointer’s memory into this pointer’s memory. ``` func copyMemory(from source: UnsafeRawPointer, byteCount: Int) ``` ## Parameters `source` A pointer to the memory to copy bytes from. The memory in the region `source..<(source + byteCount)` must be initialized to a trivial type. `byteCount` The number of bytes to copy. `byteCount` must not be negative. ## Discussion If the `byteCount` bytes of memory referenced by this pointer are bound to a type `T`, then `T` must be a trivial type, this pointer and `source` must be properly aligned for accessing `T`, and `byteCount` must be a multiple of `MemoryLayout.stride`. The memory in the region `source..<(source + byteCount)` may overlap with the memory referenced by this pointer. After calling `copyMemory(from:byteCount:)`, the `byteCount` bytes of memory referenced by this pointer are initialized to raw bytes. If the memory is bound to type `T`, then it contains values of type `T`. --- 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)