First install autoconf, php pear and curl
pacman -Syu autoconf php-pear curl
Then install pecl_http and iconv
pear install pecl.php.net/pecl_iconv
pear install pecl.php.net/pecl_http, iconv
Edit your php.ini
nano /etc/php/php.ini
Add
extension=http.so
Restart apache
rc.d restart httpd