Problem with the accents in url

Instead of manually listing the "problematic" characters, what you can do is a regular expression to say: "all non-ASCII characters".

The ASCII characters are those between \x00 and \x7F . ( This I learned in StackOverflow ) The printable ASCII characters are between \x20 and \x7F , therefore to eliminate everything that does not fall in that range you do:

$jstring2 = preg_replace('/[^(\x20-\x7F)]*/', '', $jcountry);

From then on it is up to you what to do with the spaces and punctuation marks.

If what you are looking for is to generate a URL without special characters, such as: /search/region-de-arica-y-parinacota/aysen

What you would be missing is to replace each caracter acentuado with its corresponding without accent .

Example:

<?php

function urlCleanString($str) {
    // Quitamos los caracteres "desconocidos"
    $str = preg_replace('/[^a-zA-Z0-9ñÑáéíóúÁÉÍÓÚ ]/', '', $str);

    // Reemplazamos los espacios por guiones (-)
    $str = strtolower(preg_replace('/\s+/', '-', $str));

    // Reemplazamos la caracteres acentuados
    return str_replace(array('á','é','í','ó','ú','ñ'), array('a','e','i','o','u','n'), $str);
}

$jcountry = 'Región de arica y parinacota';
$jcity = 'Aysén';

echo 'search/'.urlCleanString($jcountry).'/'.urlCleanString($jcity);

//Output: search/region-de-arica-y-parinacota/aysen

Demo

PD : Your RegExp to remove "unknown characters" was missing the space ( ) and that's why your $paramN had no hyphens ( - )

It's actually quite simple:

We load the helper text in the controller, where you need it or directly in the autoload

// Cargamos el helper
$this->load->helper('text');

// Forma de Implementación
$str = 'áéíóú';
$str = convert_accented_characters($str);
echo $str; // aeiou