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。 就是想不通...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 更新

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

这给出了以 10^-9 秒为单位的秒的小数部分。 对于毫秒，只需将此值除以 10⁶：

let milliSeconds = nanoSeconds / 1_000_000

或者，如果您只想显示小数 秒，使用NSDateFormatter 和SSS 格式。示例：

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

Swift 3 更新

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