[ Swift ] Date Fomatter

// date fomatter
func formattedDateString(dateString: String) -> String {
    let formatter = DateFormatter()
    formatter.dateFormat = "yyyy.MM.dd"

    if let date = formatter.date(from: dateString) {
//            formatter.dateFormat = "M/d"
        formatter.dateFormat = "yy.MM.dd"
        return formatter.string(from: date)
    }
    else {
        return ""
    }
}