Yes, Flats has MFi controller support!
Flats on iOS does support controllers and is compatible with the MFI standard.
Smart menu: You can play singleplayer mode while waiting other players in multiplayer mode.
Anytime you can switch multiplayer to singleplayer or singleplayer to multiplayer.
You don't have to signup or register to play multiplayer, just download and play.
This software includes the work that is distributed in the Apache License 2.0..
Flats supports MFi controllers.