돈자리수표시.swift

func moneyPlaceHolder(money: Int) -> String {
    guard money >= 0 else { return "" }
    
    let moneyString = String(money)
    let moneyCount = moneyString.count
    let insertPlaceCount = 3
    
    if moneyCount <= insertPlaceCount {
        return moneyString
    }
    
    let index0: String.Index = moneyString.startIndex
    var resultString = ""
    var loopIndex = 0
    for i in (0 ..< moneyCount).reversed() {
        resultString += String(moneyString[moneyString.index(index0, offsetBy: i)])
        loopIndex += 1
        if loopIndex >= insertPlaceCount {
            resultString += ","
            loopIndex = 0
        }
    }
    return String(resultString.reversed())
}