Apple Swift:如何以1/100或1/1000获得当前秒数？

Question

func updateTime() {
    var date = NSDate()
    var calendar = NSCalendar.currentCalendar()
    var components = calendar.components(.CalendarUnitSecond, fromDate: date)
    var hour = components.hour
    var minutes = components.minute
    var seconds = components.second
    counterLabel.text = "\(seconds)"

    var myIndicator = counterLabel.text?.toInt()

    if myIndicator! % 2 == 0 {
        // do this
    } else {
       // do that
    }
}

我想知道如何更改此代码,以便在counterlabel.text中显示1/10或1/100或1/1000秒.只是想不出来......谢谢!

Answer 1

有一个纳秒的日历单位:

let date = NSDate()
let calendar = NSCalendar.currentCalendar()
let components = calendar.components(.CalendarUnitNanosecond, fromDate: date)
let nanoSeconds = components.nanosecond

Swift 3的更新

let date = Date()
let calendar = NSCalendar.current
let components = calendar.dateComponents([.nanosecond], from: date)
let nanoSeconds = components.nanosecond

这给出了秒的小数部分,以10 ^-9秒为单位.对于毫秒,只需将此值除以10 ⁶:

let milliSeconds = nanoSeconds / 1_000_000

或者,如果您只想显示小数秒,请使用a NSDateFormatter和SSS格式.例:

let fmt = NSDateFormatter()
fmt.dateFormat = "HH:mm:ss.SSS"
counterLabel.text = fmt.stringFromDate(date)

Swift 3的更新

let fmt = DateFormatter()
fmt.dateFormat = "HH:mm:ss.SSS"
counterLabel.text = fmt.stringFromDate(date)