<?php
if (strtolower (realpath (__FILE__)) == strtolower (realpath ($_SERVER['SCRIPT_FILENAME']))) { header ('Location: http://www.bing.ca/'); die; }

// --------------------------------------------------------
// Customize the theme
//
function HERE_theme_customize ($wp_customize)
{

// STEP 1: Define the configuration

 // --------------------------------------------------------
 $sections = array (array ('section'     => 'theme_header',
                           'title'       => __('Header', 'www'),
                           'description' => __('Configure the Header', 'www'),
                           'settings'    => array (array ('setting' => 'theme_logo',                 'label' => __('Site Logo', 'www'),      'control' => 'image'),
                                                   array ('setting' => 'theme_head_text',            'label' => __('Text in Header', 'www'), 'control' => 'textarea'))),
                    array ('section'     => 'theme_footer',
                           'title'       => __('Footer', 'www'),
                           'description' => __('Text in the footer', 'www'),
                           'settings'    => array (array ('setting' => 'theme_footer_text_id',       'label' => __('Text Block: ID or Slug', 'www')),
                                                   array ('setting' => 'theme_footer_privacy_url',   'label' => __('Link to the Privacy Page', 'www')),
                                                   array ('setting' => 'theme_footer_copyright',     'label' => __('Copyright note at left', 'www')))),
                    array ('section'     => 'theme_home_page',
                           'title'       => __('Home Page', 'www'),
                           'description' => __('Configure the Home Page', 'www'),
                           'settings'    => array (array ('setting' => 'theme_home_slider',          'label' => __('Front slider: ID or Slug', 'www')),
                                                   array ('setting' => 'theme_home_featured_title',  'label' => __('Featured posts: Title', 'www')),
                                                   array ('setting' => 'theme_home_featured_cat',    'label' => __('Featured posts: Category Slug ', 'www')),
                                                   array ('setting' => 'theme_home_portfolio_title', 'label' => __('Portfolio gallery: Title', 'www')),
                                                   array ('setting' => 'theme_home_portfolio_id',    'label' => __('Portfolio gallery: ID or Slug', 'www')),
                                                   array ('setting' => 'theme_home_why_us_title',    'label' => __('Why Us Block: Title', 'www')),
                                                   array ('setting' => 'theme_home_why_us_image',    'label' => __('Why Us Block: Image', 'www'), 'control' => 'image'),
                                                   array ('setting' => 'theme_home_why_us_id',       'label' => __('Why Us Block: ID or Slug', 'www')),
                                                   array ('setting' => 'theme_home_contact_title',   'label' => __('Contact Block: Title', 'www')),
                                                   array ('setting' => 'theme_home_contact_id',      'label' => __('Contact Block: ID or Slug', 'www')))),
                    array ('section'     => 'theme_socials',
                           'title'       => __('Social', 'www'),
                           'description' => __('Links to your Social Sites', 'www'),
                           'settings'    => array (array ('setting' => 'theme_social_facebook',       'label' => __('Facebook URL', 'www')),
                                                   array ('setting' => 'theme_social_facebook_appid', 'label' => __('Facebook App ID', 'www')),
                                                   array ('setting' => 'theme_social_twitter',        'label' => __('Twitter URL', 'www')),
                                                   array ('setting' => 'theme_social_googleplus',     'label' => __('Google+ URL', 'www')),
                                                   array ('setting' => 'theme_social_pinterest',      'label' => __('Pinterest URL', 'www')),
                                                   array ('setting' => 'theme_social_etsy',           'label' => __('Etsy URL', 'www')),
                                                   array ('setting' => 'theme_social_youtube',        'label' => __('Youtube URL', 'www')),
                                                   array ('setting' => 'theme_social_instagram',      'label' => __('Instagram URL', 'www')))),
                    array ('section'     => 'theme_counters',
                           'title'       => __('Counters', 'www'),
                           'description' => __('Code for the counters', 'www'),
                           'settings'    => array (array ('setting' => 'theme_counter_google',        'label' => __('Google Analytics', 'www'), 'control' => 'textarea'))));

// STEP 2: Call the custom function, see below the source

 HERE_customizer_register ($wp_customize, $sections);

}

// --------------------------------------------------------
// Customize the theme
// Supports text, textarea and image controls so far
function HERE_customizer_register ($wp_customize, $sections)
{
 $priority = 100;

 if (is_array ($sections))
 {
  foreach ($sections as $section)
  {
   if (!isset ($section['builtin']) || !$section['builtin'])
   {
    $wp_customize->add_section ($section['section'],
                                array ('title'       => $section['title'],
                                       'description' => $section['description'],
                                       'priority'    => (isset ($section['priority']) ? $section['priority'] : $priority++)));
   }

   if (is_array ($section['settings']))
   {
    foreach ($section['settings'] as $setting)
    {
     $wp_customize->add_setting ($setting['setting']);

     $setting['control'] = isset ($setting['control']) ? $setting['control'] : 'text';

     switch ($setting['control'])
     {
      case 'image':
       $wp_customize->add_control (new WP_Customize_Image_Control ($wp_customize,
                                                                   $setting['setting'],
                                                                   array ('label'    => $setting['label'],
                                                                          'section'  => $section['section'],
                                                                          'settings' => $setting['setting'])));
       break;

      case 'textarea':
       $wp_customize->add_control (new WP_Customize_Control ($wp_customize,
                                                             $setting['setting'],
                                                             array ('type'     => $setting['control'],
                                                                    'label'    => $setting['label'],
                                                                    'section'  => $section['section'],
                                                                    'settings' => $setting['setting'])));
       break;

      default:
       $wp_customize->add_control ($setting['setting'], array ('label'       => $setting['label'],
                                                               'section'     => $section['section']));
       break;
     }
    }
   }
  }
 }
}

To use WordPress 4 Customizer API I'd need just to do 2 steps: define a data in the array, and call a custom registering function.

2 Step use of WordPress 4 Customizer

wordpress

PHP