qml实例化c++类，报错

 

     QApplication a(argc, argv);
    qmlRegisterType<IPServer>("Qt.Ipserver", 1, 0, "IPServer");
    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("Resources/main.qml")));

在qml实例化IPServer，qml报错，

问题所在：IPServer继承了QMainWindow,导致了qml实例化报错，应继承QObject；