# read(from:at:length:into:replyHandler:) Reads the contents of the given file item. ``` func read(from item: FSItem, at offset: off_t, length: Int, into buffer: FSMutableFileDataBuffer, replyHandler reply: @escaping @Sendable (Int, (any Error)?) -> Void) ``` ## Parameters `item` The item from which to read. FSKit guarantees this item will be of type [`FSItem.ItemType.file`](/documentation/FSKit/FSItem/ItemType/file). `offset` The offset in the file from which to start reading. `length` The number of bytes to read. `buffer` A buffer to receive the bytes read from the file. `reply` A block or closure to indicate success or failure. If reading succeeds, pass the number of bytes read and a `nil` error. If reading fails, pass the number of bytes read prior to the error along with the relevant error. For an `async` Swift implementation, there’s no reply handler; simply return the byte count or throw an error. ## Discussion If the number of bytes requested exceeds the number of bytes available before the end of the file, then the call copies only those bytes to `buffer`. If `offset` points past the last valid byte of the file, don’t reply with an error but set `actuallyRead` to `0`. --- 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)