Qt MainWindow state and position save/restore

MainWindow.cpp

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    
    // ...
    
    QSettings settings;
    restoreGeometry(settings.value("geometry").toByteArray());
    restoreState(settings.value("windowState").toByteArray());
}

void MainWindow::closeEvent(QCloseEvent *event)
{
    if (QMessageBox::question(this, tr("Close"), tr("Do you want to close this Window?"), QMessageBox::No, QMessageBox::Yes) == QMessageBox::No) {
        event->ignore();
        return;
    }

    QSettings settings;
    settings.setValue("geometry", saveGeometry());
    settings.setValue("windowState", saveState());
    QMainWindow::closeEvent(event);
}