This is a simple md5 implementation.

Add a file CommonDigest.h in your project from
/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS3.0.sdk /usr/include/CommonCrypto/

  1. #import "CommonDigest.h"
  2.  
  3. + (NSString *)uniqueIDFromString:(NSString *)source
  4. {
  5.     const char *src = [[source lowercaseString] UTF8String];
  6.     unsigned char result[CC_MD5_DIGEST_LENGTH];
  7.     CC_MD5(src, strlen(src), result);
  8.  
  9.     NSString *ret = [[[NSString alloc] initWithFormat:@"%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X",
  10.                         result[0], result[1], result[2], result[3],
  11.                         result[4], result[5], result[6], result[7],
  12.                         result[8], result[9], result[10], result[11],
  13.                         result[12], result[13], result[14], result[15]
  14.                      ] autorelease];
  15.  
  16.     return ret;
  17. }

Res0urce: snipplr.com