Apple has their own framework to provide access to game controllers: Game Controller Framework Reference

I have tried it with Xbox360 Wireless and this driver, but nothing gets found:

#import <GameController/GameController.h>

for (GCController *controller in [GCController controllers]) {
    NSLog(@"CONTROLLER FOUND: %@", controller);
}

I could access it via SDL2.
So I was wondering, what would be the effort to add support for GameController Framework?