morning code challenge 8/21

codeChallengeWeek7.swift

func isTwinPrime (_ num: Int) -> Bool {
    guard checkPrime(num) else {
        return false
    }
    let numMinusTwo = num - 2
    let numPlusTwo = num + 2
    if checkPrime(numMinusTwo) || checkPrime(numPlusTwo) {
        return true
    } else {
        return false
    }
}

func checkPrime(_ num: Int) -> Bool {
    guard num > 1 else {
        return false
    }
    for i in 2..<num {
        if num % i == 0 {
            return false
        }
    }
    return true
}

isTwinPrime(5) //5 returns true.
isTwinPrime(9) //9 returns false.
isTwinPrime(7) //7 returns true.
isTwinPrime(23) //23 returns false