The FineReader PDF for Mobile search uses an imprecise search that allows n-number of errors in the request and shows all the results. The search is run in the following cases: 

• after entering at least one symbol;
• whenever entering a new character;
• when changing a search request.

At the same time, the previous search is canceled and updated.
 

You can find more information about the classification in the following articles: 

How long does it take to classify photos? 

What types of images are used in classification?

What is the accuracy of the classification in FineReader PDF for Mobile?

How to improve classification search results

Classification and recognition in FineReader PDF for Mobile