中文UrlEncode

• (NSString *)urlencode:(NSString *)urlStr
  {
  NSMutableString *output = [NSMutableString string];
  const unsigned char *source = (const unsigned char *)[urlStr UTF8String];
  int sourceLen = strlen((const char *)source);
  for (int i = 0; i < sourceLen; ++i) {
  const unsigned char thisChar = source[i];
  if (thisChar == ' '){
  [output appendString:@"+"];
  } else if (thisChar == '.' || thisChar == '-' || thisChar == '' || thisChar == '~' ||
  (thisChar >= 'a' && thisChar <= 'z') ||
  (thisChar >= 'A' && thisChar <= 'Z') ||
  (thisChar >= '0' && thisChar <= '9')) {
  [output appendFormat:@"%c", thisChar];
  } else {
  [output appendFormat:@"%%%02X", thisChar];
  }
  }
  return output;
  }