cycle.swift

func cycle<A>(coll: [A]) -> AnyIterator<A> {
    var cursor = 0
    let infiniteItems = AnyIterator { () -> A in
        let itemToReturn = coll[cursor]
        cursor += 1
        if (cursor > coll.count - 1) {
            cursor = 0
        }
        return itemToReturn
    }
    return infiniteItems
}


let ticTac = cycle(["tic", "tac"])
print(ticTac.next()) // "tic"
print(ticTac.next()) // "tac"
print(ticTac.next()) // "tic"
print(ticTac.next()) // "tac"
print(ticTac.next()) // "tic"

take.swift

func take<A>(count: Int, coll: AnyIterator<A>) -> [A] {
    var returnValue: [A] = []
    for _ in 1...count {
        returnValue.append(coll.next()!)
    }
    
    return returnValue
}

let ticTac = cycle(["tic", "tac"])
print(take(3, ticTac)) // ["tic", "tac" ,"tic"]