C++成员变量类Q_PROPERTY在QML中不可用

class MyObject : public QObject
{
    Q_OBJECT
    Q_PROPERTY(int myProperty READ getMyProperty WRITE setMyProperty NOTIFY myPropertyChanged)

public:
    int getMyProperty() const;
    void setMyProperty(int value);

signals:
    void myPropertyChanged();

private:
    int m_myProperty;
};

import QtQuick 2.0

Item {
    MyObject {
        id: myObject
        myProperty: 10
    }

    Text {
        text: "My Property: " + myObject.myProperty
    }

    Button {
        text: "Change Property"
        onClicked: {
            myObject.myProperty = 20
        }
    }
}