字符串反转 转换大小

案例描述：
字符串1：Swift NSLayoutConstraint
字符串2：Tfiws TNIartsnOctuoyalsn
按上边字符串1转换到字符串2 的规律，编写一个字符串处理函数。

<?php    header('content-type:text/html;charset=utf-8');    $str = "Swift NSLayoutConstraint";    echo $str;    echo "<br>";    $arr = str_split($str);    foreach($arr as $k => $v){        if(preg_match('/^[A-Z]$/',$v)){            $ar[] = $k;        }    }    $str1 = '';    $ars = explode(" ",$str);    foreach($ars as $k => $v){        $ar1[$k] = strtolower(strrev($v));        $str1 .= $ar1[$k]." ";    }    $str11 = str_split($str1);    foreach($ar as $k => $v){        $str11[$v] = strtoupper($str11[$v]);    }    echo implode($str11);?>