我第二次点击时为什么会得到一个零？

Question

我有一个填充了歌曲标题和艺术家的表格视图。我有一台服务器，我从那里检索歌曲。我第一次点击时效果非常好，但是当我点击另一个单元格时，我收到错误fatal error: unexpectedly found nil while unwrapping an Optional value。

func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
    let cell: VenueCell = table.cellForRowAtIndexPath(indexPath) as! VenueCell

    cell.songtitle.textColor = UIColor.whiteColor()
    cell.songartist.textColor = UIColor.whiteColor()

    controltitle.text = songtitles[indexPath.row]
    controlartist.text = songartists[indexPath.row]


    let spacesongs = songtitles[indexPath.row].stringByReplacingOccurrencesOfString(" ", withString: "%20", options: NSStringCompareOptions.LiteralSearch, range: nil)

    if let url: String = "hiding link"{

        let urlplayer = NSURL(string: url)
        let playeritem = AVPlayerItem(URL:(urlplayer)!)
        player = AVPlayer(playerItem: playeritem)
        print(url)

        NSNotificationCenter.defaultCenter().addObserver(self, selector: "playerDidFinishPlaying:", name: AVPlayerItemDidPlayToEndTimeNotification, object: playeritem)
        timer = NSTimer.scheduledTimerWithTimeInterval(0.1, target: self, selector:Selector("setProgress"), userInfo: nil, repeats: true)
        print(counter)
        print("current \(CMTimeGetSeconds(playeritem.currentTime()))")
        self.player.volume = 1.0
        self.player.rate = 1.0
        self.player.play()

        playpause.setImage(UIImage(named: "Pause"), forState: .Normal)

    }