iOS 12 Model rendering issue

Question

Having an iOS 12 model rending issue.

My app loads OBJ models with associated MTLs and textures.

On iOS 11 we were able to load up the models and they looked good:

On iOS 12, they look completely different:

We are able to make some changes after the model loads initially to make it look good, but it takes time for the iPhone to load the better looking version.

Has anyone heard about/experienced this issue and know what has changed in iOS 12 (and potentially MacOS Mojave) that is causing it?

There might be two issues: 1- texture issue (as seen in chair on left) and 2- Material/MTL issue as seen in the 'delivery drone' on the right

I don't have any code at this moment as I am not one of the developers on the project - I have been tasked with reaching out here. If you have any questions regarding the specific code I could definitely try to get some to show here. It seems to me like this might not be a code issue or bug, but rather some settings that have to changed due to changes made in iOS 12, but I can't find documentation for something that matches this.

Answer 1

I know this is not an answer, but I was asked for a screenshot. For the moment I use the OpenGL renderer instead of Metal as a workaround.

Answer 2

I solve the same issue by convert .obj file to .scn files in Xcode, and use this scenes as nodes. Editor -> Convert to SceneKit file format (.scn)

screenshot of this menu