PHP replacing special characters like à->a, è->e

gistfile1.php

  // http://stackoverflow.com/questions/10152894/php-replacing-special-characters-like-a-a-e-e?answertab=votes#tab-top
  
    // PHP.net User notes
    <?php
    $string = "ʿABBĀSĀBĀD";

    echo iconv('UTF-8', 'ISO-8859-1//TRANSLIT', $string);
    // output: [nothing, and you get a notice]

    echo iconv('UTF-8', 'ISO-8859-1//IGNORE', $string);
    // output: ABBSBD

    echo iconv('UTF-8', 'ISO-8859-1//TRANSLIT//IGNORE', $string);
    // output: ABBASABAD
    // Yay! That's what I wanted!

    ?>

The above code now gives � instead e.
is there any other option available ?

it fails for me, it removes the ẫ char
"key: FirstName | value: Vẫn Hon | processed: Vn Hon"