objective-c - Get a NSString encrypted from an original NSString

Question

I found a lot of subjects about encryption and AES/DES but I didn't found a way to get a NSString encrypted from an original NSString. Is there a way to have a NSString instead of getting NSData ?

I want to use my NSString encrypted in order to create an URL. I want to transform something like : http://test.fr/143 in something like http://test.fr/AydgzeifgzZEH239c2390304kdjlad and have the possibility to decrypt this in order to get my 143 string again.