How to encrypt credit card number in iPhone

I want to send credit card number through post method but the credit card number should be in encrypted form. How to encrypt it?

My code is:

NSString *fName = firstName.text;
NSString *lName = lastName.text;
NSString *phone = phoneNumber.text;
NSString *emailid = email.text;
NSString *cardNumber = creditCardNumber.text;
NSString *ID = particularEventPaidId;
NSString *postData = [NSString stringWithFormat:@"id=%@&firstname=%@&lastname=%@&phone=%@&email=%@&creditcard=%@",ID,fName,lName,phone,emailid,cardNumber];
NSString *postLength = [NSString stringWithFormat:@"%d", [postData length]];
NSLog(@"postLength is: %@",postLength);

NSURL *url = [NSURL URLWithString:@"http://cfcdi.org/eassociation/web-service/event-register.php"];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
[request setHTTPMethod:@"POST"];
NSData *requestBody = [开发者_开发技巧postData dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];
[request setValue:postLength forHTTPHeaderField:@"Content-Length"];
[request setHTTPBody:requestBody];
[request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"content-type"];
NSURLResponse *response;
NSError *requestError;
[NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&requestError];

if(requestError==nil)
    NSLog(@"Error is nil");
else
    NSLog(@"Error is not nil");
NSLog(@"success!");

In above I want to send credit card number in encrypted form.

1. Make sure you use a secure server when you prepare to launch your application (https://)
2. Look at some AES encryption examples and Apples CryptoExercise.

Apple's CryptoExercise

AES Encryption for an NSString on the iPhone