In Alfresco Explorer, the folder/category restriction is the native function for advanced search. There is no such function for advanced search in Share. For better performance, it’s important to have this feature for the advanced search in Alfresco Share.
The advanced search in Share is based on form service. And the form service allows showing the existing fields and the potential fields for a content type. To get category restriction, the field “cm:categories” can be introduced into the search form like the following:
<show id="cm:categories" />