previewText property

Implementation

String get previewText {
  if (revoked) {
    return isFlashRead ? '[已焚毁]' : '[已撤回]';
  }
  if (isFlashRead) return '[闪阅消息]';
  final content = extra?['content']?.toString();
  return MsgType.previewText(msgType, content: content, extra: extra);
}