[C++][Qt]How to sort QComboBox.

    combo->addItems(QStringList() << "B" << "C" << "A"); // "B","C","A"
    // for sorting you need the following 4 lines
    QSortFilterProxyModel* proxy = new QSortFilterProxyModel(combo);  // <--
    proxy->setSourceModel(combo->model());                            // <--
    // combo's current model must be reparented,
    // otherwise QComboBox::setModel() will delete it
    combo->model()->setParent(proxy);                                 // <--
    combo->setModel(proxy);                                           // <--
    // sort
    combo->model()->sort(0); // "A","B","C"