Crypto class PHP to objective-C

I have a PHP class to encrypt and decrypt strings:

$ralphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890,.:;?~@#\$%^&*()_+-=][}{><";
$alphabet = $ralphabet . $ralphabet;


function encrypt ($password,$strtoencrypt) {

global $ralphabet;
global $alphabet;

 for( $i=0; $i<strlen($password); $i++ )
 {
   $cur_pswd_ltr = substr($password,$i,1);
   $pos_alpha_ary[] = substr(strstr($alphabet,$cur_pswd_ltr),0开发者_运维技巧,strlen($ralphabet));
  }

$i=0;
$n = 0;
$nn = strlen($password);
$c = strlen($strtoencrypt);

$encrypted_string = "";

 while($i<$c)
 {
   $encrypted_string .= substr($pos_alpha_ary[$n],strpos($ralphabet,substr($strtoencrypt,$i,1)),1);

   $n++;
   if($n==$nn) $n = 0;
   $i++;
  }

return $encrypted_string;

}

It receives the string to encrypt, and a KEY.

I need to translate it to objective-C, but I don't understand PHP much.

What are the equivalents to the functions that are used in the PHP class, so that I can create the class in objective-C?

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All the functions you can find in this code come directly from the C side of PHP, doing man theFunction will give you all the informations you need about them.

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30 seconds in Google led me to this, I suppose if you invest a little time you can find the docs for the rest of the functions.