For anyone who might be interested, the X Air FMP Remote App for iPhone and iPad is available in the App Store:
The App permits remote control of Faders, Mutes and Pans in the X Air series of consoles, on both iPhone and iPad.
X Air FMP Remote has been renamed to 'Air Pro MX', and the latest version (version 5.0) is now available in the App Store. This is a total rebuild from the ground up in Swift 5, it includes full metering, and the option to buy Dynamics and EQ Packs as In-App-Purchases. It supports both the X Air and M Air series of consoles, and runs on both iPhone and iPad. The Dynamics Pack is available to buy now, and the EQ Pack will be available in around a week's time.