JSON转数组 获取有关问题

$cityArry = '[
        {
            "省": "台湾",
            "市": [
                {
                    "市名": "台北县",
                    "编码": "101340101"
                },
                {
                    "市名": "台中",
                    "编码": "101340401"
                }
            ]
        }
    ]';  


$temp1 = json_decode($cityArry);  

$arr = array ($temp1);

print_r($arr[0]);

?>

$arr = json_decode($cityArry, true);  
foreach($arr[0] as $key=>$item) {
  echo $item['省'], PHP_EOL;
  foreach($item['市'] as $row) {
    echo "$row[编码] => $row[市名]\n";
  }
}