Сортировать Переполнение стека в массиве SimpleXML

У меня есть следующий XML-файл timezone; Я хочу отсортировать по названию часового пояса, но это тоже сортирует подкатегорию. Я просто хочу отсортировать страну по часовому поясу.

SimpleXMLElement Object
(
[code] => CZ
[timezone] => Europe/Prague
)
SimpleXMLElement Object
(
[code] => AQ
[timezone] => Antarctica/South_Pole
)
SimpleXMLElement Object
(
[code] => BB
[timezone] => America/Barbados
)
SimpleXMLElement Object
(
[code] => IL
[timezone] => Asia/Jerusalem
)
SimpleXMLElement Object
(
[code] => BY
[timezone] => Europe/Minsk
)
SimpleXMLElement Object
(
[code] => WF
[timezone] => Pacific/Wallis
)
SimpleXMLElement Object
(
[code] => ST
[timezone] => Africa/Sao_Tome
)
SimpleXMLElement Object
(
[code] => ES
[timezone] => Europe/Madrid
[zones] => SimpleXMLElement Object
(
[zone] => Array
(
[0] => SimpleXMLElement Object
(
[codigo] => 07
[timezone] => Europe/Madrid
)

[1] => SimpleXMLElement Object
(
[codigo] => 27
[timezone] => Europe/Madrid
)

[2] => SimpleXMLElement Object
(
[codigo] => 29
[timezone] => Europe/Madrid
)

[3] => SimpleXMLElement Object
(
[codigo] => 31
[timezone] => Europe/Madrid
)

[4] => SimpleXMLElement Object
(
[codigo] => 32
[timezone] => Europe/Madrid
)

[5] => SimpleXMLElement Object
(
[codigo] => 34
[timezone] => Europe/Madrid
)

[6] => SimpleXMLElement Object
(
[codigo] => 39
[timezone] => Europe/Madrid
)

[7] => SimpleXMLElement Object
(
[codigo] => 51
[timezone] => Africa/Ceuta
)

[8] => SimpleXMLElement Object
(
[codigo] => 52
[timezone] => Europe/Madrid
)

[9] => SimpleXMLElement Object
(
[codigo] => 53
[timezone] => Atlantic/Canary
)

[10] => SimpleXMLElement Object
(
[codigo] => 54
[timezone] => Europe/Madrid
)

[11] => SimpleXMLElement Object
(
[codigo] => 54
[timezone] => Europe/Madrid
)

[12] => SimpleXMLElement Object
(
[codigo] => 54
[timezone] => Europe/Madrid
)

[13] => SimpleXMLElement Object
(
[codigo] => 55
[timezone] => Europe/Madrid
)

[14] => SimpleXMLElement Object
(
[codigo] => 56
[timezone] => Europe/Madrid
)

[15] => SimpleXMLElement Object
(
[codigo] => 57
[timezone] => Europe/Madrid
)

[16] => SimpleXMLElement Object
(
[codigo] => 58
[timezone] => Europe/Madrid
)

[17] => SimpleXMLElement Object
(
[codigo] => 59
[timezone] => Europe/Madrid
)

[18] => SimpleXMLElement Object
(
[codigo] => 60
[timezone] => Europe/Madrid
)
)
)
)
SimpleXMLElement Object
(
[code] => FK
[timezone] => Atlantic/Stanley
)
SimpleXMLElement Object
(
[code] => CA
[timezone] => America/Edmonton
[zones] => SimpleXMLElement Object
(
[zone] => Array
(
[0] => SimpleXMLElement Object
(
[codigo] => AB
[timezone] => America/Edmonton
)

[1] => SimpleXMLElement Object
(
[codigo] => BC
[timezone] => America/Vancouver
)

[2] => SimpleXMLElement Object
(
[codigo] => MB
[timezone] => America/Winnipeg
)

[3] => SimpleXMLElement Object
(
[codigo] => NB
[timezone] => America/Halifax
)

[4] => SimpleXMLElement Object
(
[codigo] => NL
[timezone] => America/St_Johns
)

[5] => SimpleXMLElement Object
(
[codigo] => NS
[timezone] => America/Halifax
)

[6] => SimpleXMLElement Object
(
[codigo] => NT
[timezone] => America/Yellowknife
)

[7] => SimpleXMLElement Object
(
[codigo] => NU
[timezone] => America/Rankin_Inlet
)

[8] => SimpleXMLElement Object
(
[codigo] => ON
[timezone] => America/Toronto
)

[9] => SimpleXMLElement Object
(
[codigo] => PE
[timezone] => America/Halifax
)

[10] => SimpleXMLElement Object
(
[codigo] => QC
[timezone] => America/Montreal
)

[11] => SimpleXMLElement Object
(
[codigo] => SK
[timezone] => America/Regina
)

[12] => SimpleXMLElement Object
(
[codigo] => YT
[timezone] => America/Whitehorse
)
)
)
)
SimpleXMLElement Object
(
[code] => KI
[timezone] => Indian/Comoro
)

Моя PHP-программа:

$xmltimeZones = simplexml_load_file(COREPATH.'includes/xml/inc.timezones.xml');
$timeZonesObj = $xmltimeZones->xpath("//timezones/country");
foreach ($timeZonesObj as $timeZone){
if(isset($timeZone->zones) && $timeZone->zones !=''){
foreach ($timeZone->zones->zone as $value) {
$SubZonas[(string)$value->codigo] = (string)$value->timezone;
sort($SubZonas);
}
$timeZones[(string)$timeZone->timezone] = $SubZonas;
} else {
$timeZones[(string)$timeZone->code] = (string)$timeZone->timezone;
}
}
return $timeZones;
}