Would you be able to elaborate on what you mean by search tool by attribute?
I have an addin i created that somewhat lets you search by attributes but it is somewhat limited in scope.
Basically a first dropdown(combobox) presents a list of all features in your table of contents(TOC).
A second combobox gives you all the fields in that layer.
A third combobox provides a list of all unique attributes within the selected field.
Given those critera it queries the feature and highlights what you searched for in blue on the map and displays your items within a table.
The limitiations of this currently is that:
A: you are limited to searching for only 1 attribute value at a time
B: Currently it only is made for Package Child Layers in a layer package (but this could be fixed and expanded fairly quickly)
C: It looks at each individual attribute in the table by looping through which (though not the best method) was the only method i could figure out. It will be slow on very large datasets but will function.
😧 It doesn't return the symbology of the layer you queried. I have no clue how ESRI does it. I assume since there is shapefile sitting locally on your machine they pull from that but since the layers are contained as packages in the TOC I don't believe its possible to leverage the SDK to pull the symbology, hence the blue highlighting and the table return.
If your interested i could expand the feature types and post this online.