在 swift 中,我该怎么做?

In swift, how do I do this?

我的英语不够好,无法搜索问题。所以,我不得不写在这里。对于 ex,我的整数是 600000000。我想这样转换:600,000,000。我该怎么做?

extension Int {
    struct Number {
        static let formatter = NSNumberFormatter()
    }
    var addThousandSeparator:String {
        Number.formatter.groupingSeparator = "."
        Number.formatter.numberStyle = NSNumberFormatterStyle.DecimalStyle
        return Number.formatter.stringFromNumber(self)!
    }
}

let myInteger = 600000000
let myIntegerString = myInteger.addThousandSeparator  // "600.000.000"