icon 数字のカンマ区切り文字列 (2015/11/12)
数字をカンマ区切りの文字列にする場合、NSNumberFormatter()を利用する

        let formatter = NSNumberFormatter()
        formatter.numberStyle = NSNumberFormatterStyle.DecimalStyle
        formatter.groupingSeparator = ","
        formatter.groupingSize = 3

        let number:Int = 3480
        let stringNumber:String? = formatter.stringFromNumber(number)
        print(stringNumber)