UITableView going out of view - ios

Question

i have a UITableView with multiple selection enabled with checkmarks. When i make selection that are all visible in the view, i don't run into any errors. However, if i scroll down further and place a selected item out of view, i get errors and even though the row stays selected, the checkmark goes away.
import Foundation
import Parse
import UIKit
class customerMenuVC: UIViewController, UITableViewDelegate, UITableViewDataSource {
#IBOutlet weak var menuTV: UITableView!
var menuItems: [String] = ["Hello"]
var menuPrices: [Double] = [0.0]
var orderSelection: [String] = []
var priceSelection: [Double] = []
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int
{
return menuItems.count
}
func tableView(tableView: UITableView, numberOfColumnsInSection section: Int) -> Int
{
return 1;
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell
{
let cell:UITableViewCell = UITableViewCell(style: UITableViewCellStyle.Subtitle, reuseIdentifier: "mycell")
cell.textLabel!.text = "\(menuItems[indexPath.row])\t $\(menuPrices[indexPath.row])"
return cell
}
func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath)
{
//tableView.deselectRowAtIndexPath(indexPath, animated: true)
let cell = tableView.cellForRowAtIndexPath(indexPath)
cell!.accessoryType = .Checkmark
orderSelection.append(cell!.textLabel!.text!)
}
func tableView(tableView: UITableView, didDeselectRowAtIndexPath indexPath: NSIndexPath)
{
let cell = tableView.cellForRowAtIndexPath(indexPath)
cell!.accessoryType = .None
}
override func viewDidLoad() {
super.viewDidLoad()
menuTV.allowsMultipleSelection = true
let resMenu = resUser.sharedInstance
var resName = resMenu.nameStr
var resID = resMenu.idStr
var menuQ = PFQuery(className: "menu")
menuQ.getObjectInBackgroundWithId(resID){
(menus: PFObject?, error: NSError?) -> Void in
if error == nil && menus != nil {
let items: [String] = menus?.objectForKey("menuItems") as! Array
let prices: [Double] = menus?.objectForKey("menuPrices") as! Array
self.menuItems = items
self.menuPrices = prices
self.menuTV.reloadData()
}
}
}
#IBAction func continueButton(sender: AnyObject) {
let selections = menuTV.indexPathsForSelectedRows() as! [NSIndexPath]
var indexCount = selections.count
println(indexCount)
var x = 0
while x < indexCount
{
println(x)
let currentCell = menuTV.cellForRowAtIndexPath(selections[x]) as? UITableViewCell?;
println(x)
println(selections[x].row.description)
orderSelection.append(currentCell!!.textLabel!.text!)
println(orderSelection[x])
x++
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}

Answer 1

This is how table views work.
When a cells scrolls off-screen, it gets tossed into the recycle queue and then used again to display data for a different indexPath in your data.
Any time the user makes any changes to the data for a cell you should save it to your data model (usually an array of information, or maybe an array of arrays if you're using a sectioned table view.) Then you should tell the table view to redisplay the changed cell. The cellForRowAtIndexPath method picks up the changed data and shows the changes to the cell. If the cell scrolls off-screen and then scrolls back on-screen, it gets displayed with the correct settings.
This applies to keeping track of which cells are selected as well.