fatal error: unexpectedly found nil while unwrapping an Optional value

在这条线上：

var cell = tableView.dequeueReusableCellWithIdentifier("rideCell")  as! RideCell

当我切换回UITableViewController时,这个错误消失了,一切都很好,但是我刚刚再次测试了它,它再次给了我那个错误.

有人有什么建议吗？它适用于普通的表视图,就在我进行搜索时它会崩溃.标识符绝对正确.

谢谢！

编辑：

全功能：

override func tableView(tableView: UITableView,cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    var cell = tableView.dequeueReusableCellWithIdentifier("rideCell",forIndexPath: indexPath) as! RideCell

    var ride: Ride

    if tableView == self.searchDisplayController?.searchResultsTableView {
        ride = DataManager.sharedInstance.getRideByName(searchResults[indexPath.row].name)!
    } else {
        ride = DataManager.sharedInstance.rideAtLocation(indexPath.row)!
    }

    cell.rideNameLabel.text = ride.name

    var dateSinceUpdate = NSDate().timeIntervalSinceDate(ride.updated!)
    var secondsSinceUpdate = Int(dateSinceUpdate)
    var timeSinceUpdate = printSecondsConvert(secondsSinceUpdate)

    cell.updatedLabel.text = timeSinceUpdate

    if ride.waitTime == "Closed" {
        cell.waitTimeLabel.text = ride.waitTime!
        cell.timeBackgroundView.backgroundColor = getColorFromNumber(80)
        cell.waitTimeLabel.font = UIFont(name: "Avenir",size: 13)
    } else {
        cell.waitTimeLabel.text = "\(ride.waitTime!)m"
        cell.timeBackgroundView.backgroundColor = getColorFromNumber(ride.waitTime!.toInt()!)
        cell.waitTimeLabel.font = UIFont(name: "Avenir",size: 17)
    }

    AsyncImageLoader.sharedLoader().cancelLoadingURL(cell.rideImageView.imageURL)
    cell.rideImageView.image = UIImage(named: "Unloaded")
    cell.rideImageView.imageURL = NSURL(string: ride.rideImageSmall!)

    return cell
}