反转时间标签

首先,您需要创建 NSAttributedString 用你的时间格式要求如下

func timeLeftExtended(date:Date) ->NSAttributedString{

    let cal = Calendar.current
    let now = Date()
    let calendarUnits:NSCalendar.Unit = [NSCalendar.Unit.day, NSCalendar.Unit.hour, NSCalendar.Unit.minute, NSCalendar.Unit.second]
    let components = (cal as NSCalendar).components(calendarUnits, from: now, to: date, options: [])

    let fullCountDownStr = "\(components.day!.description)d " + "\(components.hour!.description)h " + "\(components.minute!.description)m " + "\(components.second!.description)s "

    let mutableStr = NSMutableAttributedString(string: fullCountDownStr, attributes: [NSAttributedStringKey.foregroundColor:UIColor.white])

    for (index,char) in mutableStr.string.enumerated()
    {
        if(char == "d" || char == "h" || char == "m" || char == "s")
        {
            mutableStr.removeAttribute(NSAttributedStringKey.foregroundColor, range: NSMakeRange(index, 1))
            mutableStr.addAttributes([NSAttributedStringKey.foregroundColor : UIColor.lightGray], range: NSMakeRange(index, 1))
        }
    }

    return mutableStr
}

之后,您需要声明要更新剩余时间的标签

@IBOutlet weak var lblTimeRemaining: UILabel!

并添加计时器和标志,以了解计时器何时工作

fileprivate var timeWorking : Bool = false
var timer:Timer?

我们在这里设置计时器

func setupWith()
{ 
    if(!timeWorking)
    {
        timer = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(self.updateCountDown), userInfo: nil, repeats: true)
        self.timeWorking = true
    }

}

此方法将每秒执行1次以更新计数

@objc func updateCountDown()
{
    self.lblTimeRemaining.attributedText = self.timeLeftExtended(date:Date.distantFuture)
}

结果