How to upload images with tabular input

Hello. Quite a small chance on Palm Sunday.

I´m struggling with tabular input and image upload. I´m not using any extensions/widgets. Form works perfectly, but - without image upload.

I created EventForm (single form) and EventArtwork (can be multiple)

I have a function handlePostSave, which I usually use like this in actions (eg actionCreate), but this doesn’t work for arrays:

    public function actionCreate()
        $model = new EventArtwork();

        return $this->render('create', [
            'model' => $model,

What I have done already is in Gist. What I’m doing wrong?

Thank you

I don’t see anywhere where you actually saving upload in your code