iOS MD5編碼

#import <CommonCrypto/CommonDigest.h>

@implementation NSString(MD5)

- (NSString*)MD5

{

// Create pointer to the string as UTF8

  const char *ptr = [self UTF8String];

  // Create byte array of unsigned chars

  unsigned char md5Buffer[CC_MD5_DIGEST_LENGTH];

// Create 16 bytes MD5 hash value, store in buffer

  CC_MD5(ptr, strlen(ptr), md5Buffer);

// Convert unsigned char buffer to NSString of hex values

  NSMutableString *output = [NSMutableString stringWithCapacity:CC_MD5_DIGEST_LENGTH * 2];

  for(int i = 0; i < CC_MD5_DIGEST_LENGTH; i++) 

[output appendFormat:@"%02x",md5Buffer[i]];

  return output;

}

@end