Swift UITableView really slow

Question

I have a simple model E-Numbers and it reads from a .csv file. I cache the data into a variable eNummers in my ViewController so I can do basic array operations, such as eNummers[0], eNummers[1].

I read from the array in tableView:cellForRowAtIndexPath, but when I scroll the tableView it is really really slow and laggy. How can I optimize this:

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

        if cell == nil {
            cell = UITableViewCell(style: UITableViewCellStyle.Value1, reuseIdentifier: "globalCell")
        }

        if (self.eNummers?.getAllNummers().rows[indexPath.row] != nil) {
            cell.textLabel?.text = self.eNummers?.getAllNummers().rows[indexPath.row][0]
            cell.detailTextLabel?.text = self.eNummers?.getAllNummers().rows[indexPath.row][1]

            switch (self.eNummers?.getAllNummers().rows[indexPath.row][2])! {
                case "GOOD":
                    cell.textLabel?.textColor = UIColor.greenColor()
                break
                case "MODERATE":
                    cell.textLabel?.textColor = UIColor.orangeColor()
                break
                case "BAD":
                    cell.textLabel?.textColor = UIColor.redColor()
                break
                default:
                    cell.textLabel?.textColor = UIColor.blackColor()
                break
            }

        }

        return cell
    }

func getAllNummers() -> CSwiftV { let nummers = CSwiftV(String: self.contents as! String) return nummers } — jbehrens94
– jbehrens94, Commented Jul 25, 2015 at 10:41
You should make the call to getAllNummers once and then just access the array directly in cellForRowAtIndexPath. Also, if you have registered your cell class or are using a storyboard then dequeueReusableCellWithIdentifier can't return. Il - this would seem to be the case since you have used as! which will throw an exception if nil is returned. — Paulw11
– Paulw11, Commented Jul 25, 2015 at 11:06

Paul.s · Accepted Answer · 2015-07-25 10:48:46Z

3

Your function getAllNummers() is loading a CSV file and parsing it 4 times for every cell. This will be your big slow down. You should load and parse the file once and store the values in a property and then use the property to access the values you need

answered Jul 25, 2015 at 10:48

Paul.s

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1 Comment

jbehrens94 Over a year ago

This solved my problem, thank you very much! :) To clarify: I added the parsing part to the init constructor of my model, then called a property in tableView.

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