With the help of a collegue, I rewrote the code for my purpose (and it works) :
function sortByGroup($a, $b) {
if ($a['partner-category'] > $b['partner-category']) {
return -1;
} elseif ($a['partner-category'] < $b['partner-category']) {
return 1;
}
return 0;
}
$partnerArray = get_field('partner');
if (!empty($partnerArray)) {
usort($partnerArray, 'sortByGroup');
$last_group = ''; // initialize the group name
foreach ($partnerArray as $partner) {
$this_group = $partner['partner-category'];
if ($this_group != $last_group) {
$last_group = $this_group;
echo '<h3>',$partner['partner-category'],'</h3>';
}
if ($partner['partner-website']) {
$partner_bloc = '<a href="'.$partner['partner-website'].'">'.$partner['partner-name'].'</a>';
}
echo $partner_bloc;
} // end foreach
} // end if personArray
The line $last_group = $this_group; was missing in order to display the H3 only one time by group. And the sorting function has been inverted in order to reflect the backend order (from top to bottom).
