ios - 如何在 UICollectionViewCell 上使用实时计时器？

Question

我在UICollectionView中的单元格上实现了一个倒计时器，并从网络服务中获取时间，但当我返回并再次出现在UICollectionView类中时，它显示静态时间时间根据剩余的网络服务时间而减少。

但我想在每次减少一秒时实时显示它，感谢任何帮助。

我的代码:

func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell
{

    let cell = collectionView.dequeueReusableCellWithReuseIdentifier("cell", forIndexPath: indexPath) as! ManageObjectCollectionViewCell
    revealTime  = getRevealtime[indexPath.section].objectAtIndex(indexPath.row) as! Int             
    minutes = revealTime / 60           
    seconds = revealTime % 60
    cell.HourLabel.text =  "0"
    cell.MinLabel.text = NSString(string: "\(minutes)" ) as String  
    cell.sec.text = NSString(string: "\(seconds)" ) as String
}

Answer 1

    let currentTime = NSDate.timeIntervalSinceReferenceDate()

    //Find the difference between current time and start time.
    var elapsedTime: NSTimeInterval = currentTime - startTime

    //calculate the hours in elapsed time.
    let hours = UInt8(elapsedTime / 3600.0)
    elapsedTime -= (NSTimeInterval(hours) * 3600)


    //calculate the minutes in elapsed time.
    let minutes = UInt8(elapsedTime / 60.0)
    elapsedTime -= (NSTimeInterval(minutes) * 60)

    //calculate the seconds in elapsed time.
    let seconds = UInt8(elapsedTime)
    elapsedTime -= NSTimeInterval(seconds)

    //find out the fraction of milliseconds to be displayed.
   // let fraction = UInt8(elapsedTime * 100)

    //add the leading zero for minutes, seconds and millseconds and store them as string constants

    let strMinutes = String(format: "%02d", minutes)
    let strSeconds = String(format: "%02d", seconds)
    let hourss = String(format: "%02d", hours)

    //concatenate minuets, seconds and milliseconds as assign it to the UILabel
    lblDisplayTime.text = "\(hourss):\(strMinutes):\(strSeconds)"

使用此代码