Coreml: Model class has not been generated yet

It means you first need to build your project (Cmd+B). The model class is generated as part of the build process.

target -> Build Setting -> CoreML Model Compiler - Code Generation -> CoreML Generated Model Inherits NSObject -> YES

Cited from apple dev forum:

Xcode has stopped automatically adding the coreml model to the build settings of your project. To solve, go to your target, go to build phases, find compile sources and add your coreml model. After this, the model class is generated.