1.获取当前时间
var curDate = NSDate()
var dateFormatter = NSDateFormatter()
var timeFormatter = NSDateFormatter()
dateFormatter.dateFormat = “yyy-MM-dd”
timeFormatter.dateFormat = “HH:mm:ss SSS”
var dateStr = dateFormatter.stringFromDate(curDate)
var timeStr = timeFormatter.stringFromDate(curDate)

2.时间转换
func dateFromString(dateStr: String) -> NSDate? {
let dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = “yyyy-MM-dd”
let date = dateFormatter.dateFromString(dateStr)
return date
}

func stringFromDate(format: String,date: NSDate) -> String {
let locale = NSLocale.currentLocale()
let dateFormat = NSDateFormatter.dateFormatFromTemplate(format,options: 0,locale: locale)
let dateformatter = NSDateFormatter()
dateformatter.dateFormat = dateFormat
return dateformatter.stringFromDate(date)
}

3.String转换为Double
NSNumberFormatter().numberFromString(display.text!)!.doubleValue
或者
(display.text! as NSString).doubleValue

4.Double转换为String，小数为0时不显示后面的.0 let intValue = Int(newValue) if (Double(intValue) == newValue) { display.text = “(intValue)” } else { display.text = “(newValue)” }