How to save facial expressions data (including smile, eyebrow rise) into .obj file

I want to capture the series of user facial expressions data and then export into .obj file. I have used the following code to convert the scene into obj format but When I load it just displaying plane Face Mask nothing else. I also wanted to display Facial Expressions data. Can we do that or I need to store these Blend shape which is coming from FaceGeometry manually into seperate file.

I have used below code to export the scene into obj file:

let scene2 = sceneView.scene

let documentsPath1 = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!

let filename = String(format: "test.obj", timeInterval)

exportUrll = documentsPath1.appendingPathComponent(filename)

scene2.write(to: exportUrll!, options: nil, delegate: nil, progressHandler: nil);

Can you please tell me is this the correct way or else I need to use ModelIO api to create mesh?

Thanks,

Chaitanya