Issue adding new icons from file system

I’m working on a framework for use using gtk from swift, and am having a problem related to IconThemes. I’m trying to create a convenience function so that users can add custom icons using the Swift package manager’s resource bundling system. I have bundled these resources, using the directory structure for the hicolor, fallback icons, and added the resource path to the IconTheme’s search path via the gtk_icon_theme_append_search_path function. However, the icons are not recognised. I would greatly appreciate any help in resolving this issue.