# replaceSubrange(_:with:) Replaces a region of bytes in the data with new bytes from a buffer. ``` mutating func replaceSubrange(_ subrange: Range, with buffer: UnsafeBufferPointer) ``` ## Parameters `subrange` The range in the data to replace. `buffer` The replacement bytes. ## Discussion This will resize the data if required, to fit the entire contents of `buffer`. Precondition: The bounds of `subrange` must be valid indices of the collection. --- 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)