How to pick 3D objects precisely with Qt3D

[huajian]

Here is my use case:
I am using Qt3D to pick 3D objects(like a Qt3DExtras::QCuboidMesh). The default pick method is BoundingVolume, which is very coarse. I would like to switch to TrianglePicking.

My question is how to make the TrianglePicking work?
I have achieved very precise picking in QtQuick, while do not know how to do that with C++. Here is the code that does not work. Could anyone point out where should I correct?

Qt3DRender::QPickingSettings *settings = new Qt3DRender::QPickingSettings();
settings->setPickMethod(Qt3DRender::QPickingSettings::PickMethod::TrianglePicking);