array 
  'displayname' => 
    array 
      0 => string 'Аритиченк' 
      1 => string 'Івашин' 
      2 => string 'Ващенк' 
      3 => string 'Івк' 
      4 => string 'Єлюхін'
      5 => string 'Ясаєв' 
  'mail' => 
    array
      0 => string 'ar@domen.com'
      1 => string 'ivashi@domen.com'
      2 => string 'vashche@domen.com'
      3 => string 'ivk@domen.com'
      4 => string 'el@domen.com'
      5 => string 'yas@domen.com'

    function sort_uk( $a, $b ){
   $a = mb_strtoupper ( $a, 'UTF-8' );
   $b = mb_strtoupper ( $b, 'UTF-8' );
   $alphabet = array(
       'А' => 1, 'Б' => 2, 'В' => 3, 'Г' => 4, 'Д' => 5, 'Е' => 6, 'Є' => 7, 'Ж' => 8, 'З' => 9, 'И' => 10, 'І' => 11,
       'Ї' => 12, 'Й' => 13, 'К' => 14, 'Л' => 15, 'М' => 16, 'Н' => 17, 'О' => 18, 'П' => 19, 'Р' => 20, 'С' => 21, 'Т' => 22,
       'У' => 23, 'Ф' => 24, 'Х' => 25, 'Ц' => 26, 'Ч' => 27, 'Ш' => 28, 'Щ' => 29, 'Ь' => 30, 'Ю' => 31, 'Я' => 32
   );
   $lengthA = mb_strlen ( $a, 'UTF-8' );
   $lengthB = mb_strlen ( $b, 'UTF-8' );
   for( $i = 0; $i < ( $lengthA > $lengthB? $lengthB : $lengthA ); $i++ ){
       if ( $alphabet[ mb_substr( $a, $i, 1, 'UTF-8' ) ] < $alphabet[ mb_substr( $b, $i, 1, 'UTF-8' ) ] ){
           $status = -1;
           break;
       }
       elseif ( $alphabet[ mb_substr( $a, $i, 1, 'UTF-8' ) ] > $alphabet[ mb_substr( $b, $i, 1, 'UTF-8' ) ] ){
           $status = 1;
           break;
       }
       else{
           $status = 0;
       }
   }
   return $status;
}