索引到函数数组：表达式解析为未使用的l值

Question

I am trying to index into an array of functions but I get the error: "Expression resolves to an unused l-value". I have tried to google what this means but information is scarce and what I find seems unrelated. Does anyone know what I am doing wrong here? Any help would be much appreciated ! Thank you.

 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
}

Answer 1

chartsArray[0] is analagous to writing just the result of lineChart() ; you're identifying a value, but not actually doing anything with it.

Answer 2

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]()  
    }


    if indexPath.row == 1{
        chartsArray[1]()   
    }

     return cell
}