Installing "intl" extension on OSX.

1. Normally, the PHP is automatically installed on OSX. So, if you would like to use the XAMPP, or whatever apache server, you must change the path point to XAMPP. You can check the path by using:

$ which php

You should get

/Applications/XAMPP/xamppfiles/bin/php 

if not, you will get

/usr/bin/php. 

This is OSX' php. So, you have to change it by using:

$ PATH="/Applications/XAMPP/xamppfiles/bin:${PATH}"

2. Now, it's time to install `intl`. Firstly, you need to install `icu4c`

$ brew install icu4c

It takes a couple of times and returns its path to you, should look something like this:

/usr/local/Cellar/icu4c/x.x.x 

3. Next, let's install `intl` by using `pecl`

$ sudo pecl update-channels 

$  sudo pecl install intl 

It will prompt you to put the `icu4c` path.
After finish installing `icu4c`, put the following statement to `php.ini`

extension=intl.so 

4. Restart apache. and check whether it's neatly installed.

$ php -m | grep intl #should return 'intl'

That's it!