Having an app on your phone to control your ceiling fan, would be a very handed thing indeed. Typically, you would need to be in the same room as your ceiling fan in order to turn it on or off. With a ceiling fan application on your phone, you can control the ceiling fan from any room in the house. This technology is not unique to Hunter ceiling fans, of course. You can control any fan that has a WIFI receiver, generally. Most older fans do not have WIFI controllers; and not all fans manufactured today have them either. You have to look to see what kind of receiver the fan has when purchasing (reading reviews and doing research on everything you buy is helpful).
Most fans, traditionally have a receiver that operates on IR frequency. A WiFi receiver is a relatively new idea that has been available for a few years now. Sooner or later, it is likely that everything in the home will be able to be manipulated or operated through the use of your phone, computer or any Internet connected device (Internet of Things).

The Bond (above) works with the Google Home Assistant and Alexa, to control your ceiling fan by issuing voice commands. This unit is capable of controlling up to 30 ceiling fans. It does this by transmitting radio frequencies (IR) to your ceiling fans. It is able to transmit Infrared where required as well. The range of the Bond is up to and about 2,500 sq. ft., so you should be able to control all the fans in your home with this. The best part is you don’t need to change the receiver on your ceiling fans or anything like that.
It is possible to convert an existing ceiling fan to a WiFi ceiling fan, by installing a WiFi receiver. This can breathe life into some fans; however WiFi receivers may not work with all ceiling fans. Be sure to do your research to determine what ceiling fans are WiFi receiver compatible, and which ones aren’t.