Contents

write(from:startingAt:length:completionHandler:)

Writes data from from a buffer to the resource and executes a closure afterwards.

Declaration

func write(from buffer: UnsafeRawBufferPointer, startingAt offset: off_t, length: Int, completionHandler: @escaping (Int, (any Error)?) -> Void)

Parameters

  • buffer:

    A buffer to provide the data.

  • offset:

    The offset into the resource from which to start writing.

  • length:

    A maximum number of bytes to write. The completion handler receives a parameter with the actual number of bytes write.

  • completionHandler:

    A closure that executes after the write operation completes. If successful, the first parameter contains the number of bytes actually written. In the case of an error, the second parameter contains a non-nil error. This value is EFAULT if buffer is NULL, or errno if writing to the resource failed.

Discussion

For the read to succeed, requests must conform to any transfer requirements of the underlying resource. Disk drives typically require sector (physicalBlockSize) addressed operations of one or more sector-aligned offsets.

See Also

Reading and writing data