Gamekit is not recognized by my Xcode.

import GameKit

struct FactProvider {
    let facts: [String] = [
    "Ants stretch when they wake up in the morning.",
    "Ostriches can run faster than horses.",
    "Olympic gold medals are actually made mostly of silver.",
    "You are born with 300 bones; by the time you are an adult you will have 206.",
    "It takes about 8 minutes for light from the Sun to reach Earth.",
    "Some bamboo plants can grow almost a meter in just one day.",
    "The state of Florida is bigger than England.",
    "Some penguins can leap 2-3 meters out of the water.",
    "On average, it takes 66 days to form a new habit.",
    "Mammoths still walked the Earth when the Great Pyramid was being built."
    ]

    func randomFact() -> String {
        let randomNumber = GKRandomSource.sharedRandom().nextInt(upperBound: facts.count)
        return facts[randomNumber]
    }
}