Check SOS Letters

CheckSOSLetters.swift

// I publicly share any answers to "coding challenges" I receive as a part of the interview process
// copy/paste this into an Xcode playground or the code challenge repl of choice

// in a string of what should be repeating instances of "SOS", detect any errors in the SOS sequence and report the total
// number of errors

func checkSOSLettere(_ message: String) -> Int {
    var totalErrors = 0
    var currentLetterNumber = 1
    for char in message {
        let even = currentLetterNumber % 2 == 0
        if even {
            if String(char) != "O" { totalErrors += 1 }
        } else {
            if String(char) != "S" { totalErrors += 1 }
        }
        currentLetterNumber += 1
        if currentLetterNumber > 3 { currentLetterNumber = 1 }
    }
    return totalErrors
}
checkSOSLettere("SOSSSSOOO")
// 3