The POSIX file descriptor associated with the receiver.
- iOS 2.0+
- macOS 10.0+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 2.0+
You can use this method to retrieve the file descriptor while it is open. If the file handle object owns the file descriptor, you must not close it yourself. However, you can use the
close method to close the file descriptor programmatically. If you do call the
close method, subsequent calls to this method raise an exception.