UITableView is not displaying content in cell - ios

Question

For a project, I've three UITableViews in an UITabbarController. The initial view loads the tableview correctly, but when I tap on the second tab, the table loads the right amount of cells and the right cell class, but don't show the content on it.
I logged the method tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) and every cell gets the right string values.
This is the code I use:
import UIKit
import RealmSwift
class Hapjes: UIViewController, UITableViewDataSource, UITableViewDelegate {
#IBOutlet weak var tabel: UITableView!
let realm = try! Realm()
let productArray = try! Realm().objects(Product).filter("categorie = 1")
override func viewDidLoad() {
super.viewDidLoad()
tabel.dataSource = self
tabel.delegate = self
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func numberOfSectionsInTableView(tableView: UITableView) -> Int {
return 1
}
func tableView(tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
return "Hapjes"
}
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return productArray.count
}
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCellWithIdentifier("ProductenCellHapjes", forIndexPath: indexPath) as! ProductenCell
var object = productArray[indexPath.row]
cell.label.text = object.valueForKey("productNaam") as! String
cell.plaatje.image = UIImage(named: "1449032338_news.png")
let tmp = object.valueForKey("productNaam") as! String
print("Hapje: \(tmp)")
return cell
}
func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
}
}
ProductenCell.swift:
import UIKit
class ProductenCell: UITableViewCell {
#IBOutlet weak var plaatje: UIImageView!
#IBOutlet weak var label: UILabel!
}
This is the screenshot of the UI how it goes now:
http://i.stack.imgur.com/Gx0Jw.png
Thanks for your help.