Как проверить кодировку файла CSV

class DataHelper{

    private static function __renameArrayKeysRecursive($map = [], &$array = [], $level = 0, &$storage = []) {
        foreach ($map as $old => $new) {
            $old = preg_replace('/([\.]{1}+)$/', '', trim($old));
            if ($new) {
                if (!is_array($new)) {
                    $array[$new] = $array[$old];
                    $storage[$level][$old] = $new;
                    unset($array[$old]);
                } else {
                    if (isset($array[$old])) {
                        static::__renameArrayKeysRecursive($new, $array[$old], $level + 1, $storage);
                    } else if (isset($array[$storage[$level][$old]])) {
                        static::__renameArrayKeysRecursive($new, $array[$storage[$level][$old]], $level + 1, $storage);
                    }
                }
            }
        }
    }

    /**
     * Renames array keys. (add "." at the end of key in mapping array if you want rename multidimentional array key).
     * @param type $map
     * @param type $array
    */
    public static function renameArrayKeys($map = [], &$array = [])
    {
        $storage = [];
        static::__renameArrayKeysRecursive($map, $array, 0, $storage);
        unset($storage);
    }
}

Использование:

DataHelper::renameArrayKeys([
    'a' => 'b',
    'abc.' => [
       'abcd' => 'dcba'
    ]
], $yourArray);