ios – 索引到函数数组：表达式解析为未使用的l值

我试图索引到一个函数数组但我得到错误：“表达式解析为未使用的l值”.我试图谷歌这意味着什么,但信息是稀缺的,我发现似乎无关.有谁知道我在做错了什么？任何帮助将非常感激 ！谢谢.

override func tableView(tableView: UITableView,cellForRowATindexPath indexPath: NSIndexPath) -> UITableViewCell {

    var cell:UITableViewCell = myTableView.dequeueReusableCellWithIdentifier("cell") as UITableViewCell
    var chart =  cell.contentView.viewWithTag(42) as TKChart
    chart.delegate = self
    chart.removeAllData(); //needed because of cell recycling

    var userDef1 = 1
    var userDef2 = 1

    func lineChart() -> TKChart {...}
    func columnChart() -> TKChart {...}

    var chartsArray = [AnyObject]()


    if userDef1 == 1{
        chartsArray.append(lineChart())
    }


    if userDef2 == 1{
        chartsArray.append(columnChart())
    }


     if indexPath.row == 0{
        chartsArray[0]  **error: Expression resolves to an unused l-value**
    }


    if indexPath.row == 1{
        chartsArraY[1]   **error: Expression resolves to an unused l-value**
    }

    return cell
}@H_403_12@