Looking to confirm that I am doing this in the most efficient way.func convrtisbn10(isbn: String) {    var checkSum: Int = 0    var completeISBN =     let newISBN = 978 + \(isbn)    let result = String(newISBN.characters.dropLast(1))    var oddSum = 0, evenSum = 0    let reversedArray = result.characters    for (i, s) in reversedArray.enumerate() {        let digit = Int(String(s))!        if i % 2 == 0 {            evenSum += digit        } else {            oddSum += digit * 3        }    }    let total = evenSum + oddSum    let remander = total % 10    if (10 - remander) == 10 {        checkSum = 0    } else {        checkSum = 10 - remander        completeISBN = result + \(checkSum)    }    getBookInfo(completeISBN)}
Convert ISBN10 to ISBN13
swift;checksum