program a combobox in a dialog

[Devoraz]

hi. i have a dialog created using QtDesginer. can i add a combobox in that dialog using pure c++ language? example show in the code below.

void SettingsWindow::drawCombobox()
{
	QSettings settings;
 
	endDeviceCombobox = new QComboBox(ui.groupBox_2);
	endDeviceCombobox->setGeometry(QRect(190, 20, 111, 21));
	endDeviceCombobox->setEditable(false);
	endDeviceCombobox->setDuplicatesEnabled(false);
}

void SettingsWindow::drawCombobox()
{
	QSettings settings;

	endDeviceCombobox = new QComboBox(ui.groupBox_2);
	endDeviceCombobox->setGeometry(QRect(190, 20, 111, 21));
	endDeviceCombobox->setEditable(false);
	endDeviceCombobox->setDuplicatesEnabled(false);
}

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i tried but the combobox doesnt appear in the dialog. why so?