Swift：

func md5StringFromString(string :String) ->String{

        letstr = string.cString(using:String.Encoding.utf8)

        letstrLen =CUnsignedInt(string.lengthOfBytes(using:String.Encoding.utf8))

        letdigestLen =Int(CC_MD5_DIGEST_LENGTH)

        letresult =UnsafeMutablePointer.allocate(capacity: digestLen)

        CC_MD5(str!, strLen, result)

        lethash =NSMutableString()

        foriin0..< digestLen {

            hash.appendFormat("%02x", result[i])

        }

        result.deinitialize()

        returnString(format: hashasString)

    }

OC：

- (NSString*) md5Str

{

    const char *myPasswd = [self UTF8String];

    unsigned char md5c[16];

    CC_MD5(myPasswd, (CC_LONG)strlen(myPasswd), md5c);

    NSMutableString *md5Str = [NSMutableString string];

    for (int i = 0; i < 16 ; i++) {

        [md5Str appendFormat:@"%02x",md5c[i]];

    }

    return  [md5Str copy];

}