Problem:

I have to display different icons (png) in the template according to custom taxonomy (categories and subcategories).

Solution:

This is possible with a taxonomy view + a custom taxonomy image field, for example:

1) Create a taxonomy image field "my-icon"

2) Dashboard-> Toolset-> Views, Create a taxonomy view, for example "my-view"

- Query terms of your taxonomy "categories"

- Filter by:
Taxonomy is set by the current post

- In view's loop, display the custom image field "my-icon" shortcode

3) In single post content, display above taxonomy view shortcode, for example:

[wpv-view name="my-view"]

Relevant Documentation:

https://toolset.com/course-lesson/creating-custom-fields/