Swift viewController numberOfRowsInSection issue - ios

Question

I am new to swift, learning from http://www.raywenderlich.com's tutorial..
I have written this controller:
import UIKit
class ViewController: UIViewController, UITableViewDataSource {
#IBOutlet var totalTextField : UITextField!
#IBOutlet var taxPctSlider : UISlider!
#IBOutlet var taxPctLabel : UILabel!
#IBOutlet var resultsTextView : UITextView!
let tipCalc = TipCalculatorModel(total: 33.25, taxPct: 0.06)
var possibleTips = Dictionary<Int, (tipAmt:Double, total:Double)>()
var sortedKeys:[Int] = []
#IBOutlet weak var tableView: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
self.refreshUI()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func refreshUI() {
totalTextField.text = String(format: "%0.2f", tipCalc.total)
taxPctSlider.value = Float(tipCalc.taxPct) * 100.0
taxPctLabel.text = "Tax Percentage (\(Int(taxPctSlider.value))%"
}
#IBAction func calculateTapped(sender : AnyObject) {
tipCalc.total = Double((totalTextField.text as NSString).doubleValue)
possibleTips = tipCalc.returnPossibleTips()
sortedKeys = sorted(Array(possibleTips.keys))
tableView.reloadData()
}
#IBAction func taxPercentageChanged(sender: AnyObject) {
tipCalc.taxPct = Double(taxPctSlider.value) / 100
refreshUI()
}
#IBAction func viewTapped(sender: AnyObject) {
totalTextField.resignFirstResponder()
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return sortedKeys.count
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = UITableViewCell(style: UITableViewCellStyle.Value2, reuseIdentifier: nil)
let tipPct = sortedKeys[indexPath.row]
let tipAmt = possibleTips[tipPct]!.tipAmt
let total = possibleTips[tipPct]!.total
cell.textLabel?.text = "\(tipPct)%:"
cell.detailTextLabel?.text = String(format: "Tip: $%0.2f, Total: $%0.2f", tipAmt, total)
return cell
}
}
when I try to run this application, I get next error:
-[UIView tableView:numberOfRowsInSection:]: unrecognized selector sent to instance
unfortunately, I am new to this programming language and to programming for iphone, so I have no idea how to fix this issue.
I would appreciate your help on this manner

Answer 1

At runtime, your sortedKeys array doesn't have any values in it. It's only initialized as an empty array of type Int. You have it set to populate only once your calculateTapped() method is called. Therefore, numberOfRowsInSection doesn't return a valid number of rows for your table view because sortedKeys.count returns 0.