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(" | ")