function your-themme_html_head_alter(&$head_elements) {
$remove = array(
'apple-touch-icon57',
'apple-touch-icon72',
'apple-touch-icon114'
);
foreach ($remove as $key) {
if (isset($head_elements[$key])) {
unset($head_elements[$key]);
}
}
//add
$appleIcon57px = array('#tag' => 'link', '#type' => 'html_tag', '#attributes' => array('rel' => 'apple-touch-icon', 'href' => '/misc/AMU-NUMERIQUE-ICONE-57.png', 'type' => 'image/png', 'media' => 'screen and (resolution: 163dpi)'),);
$appleIcon72px = array('#tag' => 'link','#type' => 'html_tag', '#attributes' => array('rel' => 'apple-touch-icon', 'href' => '/misc/AMU-NUMERIQUE-ICONE-72.png', 'type' => 'image/png', 'media' => 'screen and (resolution: 132dpi)'),);
$appleIcon114px = array('#tag' => 'link','#type' => 'html_tag', '#attributes' => array('rel' => 'apple-touch-icon', 'href' => '/misc/AMU-NUMERIQUE-ICONE-114.png', 'type' => 'image/png', 'media' => 'screen and (resolution: 326dpi)'),);
$head_elements['apple-touch-icon57']=$appleIcon57px;
$head_elements['apple-touch-icon72']=$appleIcon72px;
$head_elements['apple-touch-icon114']=$appleIcon114px;
}