Update ACF field with post data on save or update

//update acf field with post data on save or update
//use higher number for priority so this executes after save
add_action('save_post', 'set_map_coords', 12, 3);
function set_map_coords($post_id)
{
  $posttype = get_post_type($post_id);
  
  if ('properties' == $posttype) {
    
    //get post meta data for the geocoding field
    $latlong = $_POST['martygeocoderlatlng'];
    
    //update custom field
    update_field('latlong', $latlong, $post_id);
    
  }
  return;
}