字符串连接

        let usedNum = deal.totalCount
        if usedNum != nil {
            self.info.text = "(usedNum) used"
        }
        if let date = deal.expiryDate, infoText = self.info.text {
            if usedNum != nil {
                self.info.text = infoText + " | Expires (date.month)/(date.day)/(date.year)"
            } else {
                self.info.text = infoText + "Expires (date.month)/(date.day)/(date.year)"
            }
        }

＝＝》

        var infoParts = [String]()
        if let usedNum = deal.totalCount {
            infoParts.append("(usedNum) used")
        } else {
            infoParts.append("NUM used")
        }
        if let date = deal.expiryDate {
            infoParts.append("Expires (date.month)/(date.day)/(date.year)")
        }
        self.info.text = infoParts.joinWithSeparator(" | ")