Largest Pair

largestPair.swift

func largestPair(_ num: Int) -> Int {
    var largestPair: Int = 0
    let digits = String(num).map { Int(String($0))! }
    
    for index in 0 ..< digits.count - 1 {
        let pair = digits[index]*10 + digits[index+1]
        if pair > largestPair {
            largestPair = pair
        }
    }
    return largestPair
}