Issues with using PHP Swift Mailer - php

Question

What I have done:
) Downloaded Swift-4.1.5.tar
) Extracted it
) Uploaded to my host in /public_html/domain/lib using FileZilla
) Made a new script using the code below.
) Opened it in the Browser and I got the following error below
So my question is, how am I getting the error that the file doesn't exist if It's 100% there? Thanks!
<?php
require_once '/public_html/domain/lib/swift_required.php';
?>
Warning: require_once(/public_html/domain/lib/swift_required.php) [function.require-once]: failed to open stream: No such file or directory in /home/myuser/public_html/domain/email.php on line 5
Fatal error: require_once() [function.require]: Failed opening required '/public_html/domain/lib/swift_required.php' (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/myuser/public_html/domain/email.php on line 5
Here's a screenshot of my dir from FileZilla.
http://i.imgur.com/Zsy8y.jpg

Answer 1

This is wrong:
// this is absolute path, just like /home/user or /var/www
require_once '/public_html/domain/lib/swift_required.php';
Use instead:
// this is relative path to the current file
require_once 'public_html/domain/lib/swift_required.php'; //notice: no '/' in the beggining
OR:
// so use this one if you know the whole path to the file
require_once ABSOLUTE_PATH_TO . 'public_html/domain/lib/swift_required.php';
OR:
// or use this one if you don't know the whole path
// or if the path will change (dev machine and production machine)
require_once dirname(__FILE__) . RELATIVE_PATH_TO . 'public_html/domain/lib/swift_required.php';