Contents

read(into:startingAt:length:completionHandler:)

Reads data from the resource into a buffer and executes a closure afterwards.

Declaration

func read(into buffer: UnsafeMutableRawBufferPointer, startingAt offset: off_t, length: Int, completionHandler: @escaping (Int, (any Error)?) -> Void)

Parameters

  • buffer:

    A buffer to receive the data.

  • offset:

    The offset into the resource from which to start reading.

  • length:

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

  • completionHandler:

    A closure that executes after the read operation completes. If successful, the first parameter contains the number of bytes actually read. In the case of an error, the second parameter contains a non-nil error. This value is EFAULT if buffer is nil, or errno if reading from 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