Inserindo Twig Template Engine no Codeigniter via Composer Localilzação dos arquivos: Twig.php => application/libraries/Twig.php Welcome.php => application/controller/Welcome.php autoload.php => application/config/autoload.php template.html.twig => application/views/template.html.twig index.html.twig => application/views/index.html.twig

autoload.php

<?php  if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/*
| -------------------------------------------------------------------
| AUTO-LOADER
| -------------------------------------------------------------------
| This file specifies which systems should be loaded by default.
|
| In order to keep the framework as light-weight as possible only the
| absolute minimal resources are loaded by default. For example,
| the database is not connected to automatically since no assumption
| is made regarding whether you intend to use it.  This file lets
| you globally define which systems you would like loaded with every
| request.
|
| -------------------------------------------------------------------
| Instructions
| -------------------------------------------------------------------
|
| These are the things you can load automatically:
|
| 1. Packages
| 2. Libraries
| 3. Helper files
| 4. Custom config files
| 5. Language files
| 6. Models
|
*/

/*
| -------------------------------------------------------------------
|  Auto-load Packges
| -------------------------------------------------------------------
| Prototype:
|
|  $autoload['packages'] = array(APPPATH.'third_party', '/usr/local/shared');
|
*/

$autoload['packages'] = array();


/*
| -------------------------------------------------------------------
|  Auto-load Libraries
| -------------------------------------------------------------------
| These are the classes located in the system/libraries folder
| or in your application/libraries folder.
|
| Prototype:
|
|41$autoload['libraries'] = array('database', 'session', 'xmlrpc');
*/

$autoload['libraries'] = array('database');


/*
| -------------------------------------------------------------------
|  Auto-load Helper Files
| -------------------------------------------------------------------
| Prototype:
|
|	$autoload['helper'] = array('url', 'file');
*/

$autoload['helper'] = array('url', 'file', 'form');


/*
| -------------------------------------------------------------------
|  Auto-load Config files
| -------------------------------------------------------------------
| Prototype:
|
|	$autoload['config'] = array('config1', 'config2');
|
| NOTE: This item is intended for use ONLY if you have created custom
| config files.  Otherwise, leave it blank.
|
*/

$autoload['config'] = array();


/*
| -------------------------------------------------------------------
|  Auto-load Language files
| -------------------------------------------------------------------
| Prototype:
|
|	$autoload['language'] = array('lang1', 'lang2');
|
| NOTE: Do not include the "_lang" part of your file.  For example
| "codeigniter_lang.php" would be referenced as array('codeigniter');
|
*/

$autoload['language'] = array();


/*
| -------------------------------------------------------------------
|  Auto-load Models
| -------------------------------------------------------------------
| Prototype:
|
|	$autoload['model'] = array('model1', 'model2');
|
*/

$autoload['model'] = array();


/* End of file autoload.php */
/* Location: ./application/config/autoload.php */

gistfile1.txt

<?php if (!defined('BASEPATH')) exit('No direct script access allowed');
/**
 * 
 * Arquivo inserido em application/config/twig.php 
 * 
 */
$config['template_dir'] = APPPATH.'views';

$config['cache_dir'] = APPPATH.'cache/twig';

index.html.twig

{% extends 'template.html.twig' %}

{% block content %}
  {{ title }}

  <div id="infoMessage">{{ message }}</div>

  <div class="row">
    <div class="span4 offset4">
    <h1 class="offset1">Login</h1>
    <p>Please login with your email/username and password below.</p>
      {{ form_open('auth/login', 'class="well center"')|raw }}
        <div class="input-prepend">
          <label for="password">Username:</label>
          <span class="add-on"><i class="icon-user"></i></span>
          {{ form_input( identity, 'username', 'class="input-xlarge" placeholder="username" autofocus="true"' )|raw }}
        </div>

        <div class="input-prepend">
          <label for="password">Password:</label>
          <span class="add-on"><i class="icon-lock"></i></span>
          {{ form_password( password, 'password', 'class="input-xlarge" placeholder="password" autofocus="true"' )|raw }}
        </div>
        <div class="input-prepend">
          <label for="remember">Remember Me:</label>
          {{ form_checkbox('remember', '1', FALSE, 'id="remember"')|raw }}
        </div>
        {{ form_submit('submit', 'Login', 'class="btn btn-primary"')|raw }}
      {{ form_close()|raw }}

      <p><a href="/testtwig/forgot_password">Forgot your password?</a></p>
    </div>
  </div>
  {% endblock %}

template.html.twig

<!DOCTYPE html>
<html class="no-js" lang="en">
    <head>
        <meta charset="utf-8">
        <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">

        <title>{% block title %}Template Twig{% endblock %}</title>
        <meta name="description" content="">
        <meta name="author" content="">
        <meta name="viewport" content="width=device-width">
    </head>
    <body>
        <div class="container">
            {% block content %}
                conteúdo a ser inserido
            {% endblock %}
            <hr>
            <footer>
                <p>&copy; Company 2012</p>
            </footer>
        </div>
    </body>
</html>

Twig.php

<?php if (!defined('BASEPATH')) {exit('No direct script access allowed');}
/**
 * 
 * Arquivo inserido em application/libraries/Twig.php 
 * 
 */
class Twig {

    /**
     * Referência da instância da classe CodeIgniter
     *
     * @var object
     */
    protected $CI;

    /**
     * Referência da instância da classe TWIG
     *
     * @var object
     */
    protected $_twig;

    /**
     * Diretório de templates da aplicação
     *
     * @var string
     */
    protected $_template_dir;

    /**
     * Diretório do cache dos templates da aplicação
     *
     * @var string
     */
    protected $_cache_dir;

    /***
     * Construtor da classe
     *
     * @param bool $debug verifica o valor do atributo DEBUG para a classe de template TWIG
     * @return
     */
    function __construct($debug = false)
    {
        $this->CI =& get_instance();
        $this->CI->config->load('twig');

        log_message('debug', "Twig Autoloader Loaded");

        \Twig_Autoloader::register();

        $this->_template_dir = $this->CI->config->item('template_dir');
        $this->_cache_dir = $this->CI->config->item('cache_dir');
        $loader = new \Twig_Loader_Filesystem($this->_template_dir);

        $this->_twig = new \Twig_Environment($loader, array(
            'cache' => $this->_cache_dir,
            'debug' => $debug,
            //'auto_reload' => TRUE
        ));

        foreach(get_defined_functions() as $functions) {
            foreach($functions as $function) {
                $this->_twig->addFunction($function, new Twig_Function_Function($function));
            }
        }
    }

    /**
     * Renderiza o template
     *
     * @param string $template nome do template
     * @param array $data valores a serem passados ao template
     * @return void
     */
    public function render($template, $data = array()) {
        $template = $this->_twig->loadTemplate($template);
        return $template->render($data);
    }

    /**
     * Renderiza o template verificando o tempo gasto de execução para renderização
     *
     * @param string $template nome do template
     * @param array $data valores a serem passados ao template
     * @return void
     */
    public function display($template, $data = array()) {
        $template = $this->_twig->loadTemplate($template);
        /* elapsed_time and memory_usage */
        $data['elapsed_time'] = $this->CI->benchmark->elapsed_time('total_execution_time_start', 'total_execution_time_end');
        $memory = (!function_exists('memory_get_usage')) ? '0' : round(memory_get_usage()/1024/1024, 2) . 'MB';
        $data['memory_usage'] = $memory;

        $template->display($data);
    }
    /**
     * Adiciona as funções no Twig
     * @param string $name nome da função
     * @return void
     */
    public function add_function($name)
    {
        $this->_twig->addFunction($name, new Twig_Function_Function($name));
    }

}

Welcome.php

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
 * 
 * Arquivo inserido em application/controller/Welcome.php 
 * 
 */

class Welcome extends CI_Controller {

    /**
	 * Construtor da classe
	 *
	 * @return void
	 */
	public function __construct()
	{
        parent::__construct();
	    $this->load->library('Twig');
	}

	/**
	 * Envia para a pagina index do Controller
	 * @return void
	 */
	public function index()
	{
		try{
			$data['title'] = "Testing Twig!!";
			$this->twig->display('twig/index.html.twig', $data);
		}catch(Exception $e){
			show_error($e->getMessage().' --- '.$e->getTraceAsString());
		}
	}

}

For that the file "Twig.php" works correctly is necesary to modify the line number 50:

\Twig_Autoloader::register();

to:

require_once 'Twig/Autoloader.php';
\Twig_Autoloader::register();

I had that problem.

Thank you!