iOS/Objective C: Using SecKeyWrapper to encrypt/decrypt String/Data

I want to do some RSA encryption on iPhone and after a bit of reading through iOS Developer library I found the CryptoExercise example code and its class "SecKeyWrapper"...

Can anyone tell me, how to encrypt/decrypt an NSString or NSData with a generated key pair from this class..

I've read through the code, but I didn't understand every开发者_运维技巧thing...

Thank you in advance..