I'm new to swift mesh operation. I wonder how to get vertex position in MDLMesh and modify it(used for mesh deformation). Can any one help me and thanks very much.

I'm new to SceneKit and I'm facing a major problem, when you tap a model of SCNGeometry, how to get the world coordinate of it? Or you can say how to convert the top coordinate to world coordinate. It seems that SCNView dose provide such a method, I just didn't find it. So, can anyone help me with it? Thanks very much.

Recently I was tring to develop mesh deformation in swift. The default mesh structure is SCNGeometry. I can build a model and render it. But for an imported model, it seems that there is no way to extract vertex position from it. So, is there a way to get vertex position from it, and i want to modifiy it as well. Can anyone help me with it? Thanks very much.