UICollectionView not displaying, cellForItemAt and numberOfItemsInSection not called - ios

Question

I'm trying to make an app which will display a popup with of devices with "right" or "left" names depending on whether left or right button was pressed. However, after I press left or right button, the popup appears with empty CollectionView. I colored it green to make sure that it's size is not {0, 0} and it isn't.
Popup screen
Also, I tried to make sure that cells are not bigger than the CollectionView, and it seems, that they are not. I can't put size restraints on them, though, so maybe they get resized or something.
Storyboard
I tried understanding and using solution for that question, but it seems that my situation is somewhat different. In this question cellForItemMethod was called, but in my case it wasn't and I've got no subclass of UICollectionView, which is, I guess, why I cant override intrinsicContentSize.
Here is the code for PopUpViewController:
import UIKit
protocol PopUpDelegate {
func connect(device: CollectionCell)
}
class PopUpController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource {
static let identifier: String = "PopUpController"
var parentVC: ViewController?
var left: Bool?
let reuseIdentifier = "cell"
var delegate: PopUpDelegate?
var lastSelectedCell: CollectionCell? = nil
#IBOutlet weak var collectionView: UICollectionView!
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
print("number of items in section called")
if (left!) {
return (parentVC!.leftDevices.count)
} else {
return (parentVC!.rightDevices.count)
}
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
print("cell for item called")
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath as IndexPath) as! CollectionCell
print("left: ", left!)
if (left!) {
cell.displayDevice(device: parentVC!.leftDevices[indexPath.row])
} else {
cell.displayDevice(device: parentVC!.rightDevices[indexPath.row])
}
cell.backgroundColor = UIColor.white
cell.selectButton.setTitleColor(UIColor.black, for: UIControl.State.normal)
cell.selectButton.setImage(UIImage(named: "unselectedButton"), for: UIControl.State.normal)
return cell
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
print("You selected cell #\(indexPath.item)!")
let cell = collectionView.cellForItem(at: indexPath) as! CollectionCell
cell.setSelected()
lastSelectedCell?.setUnselected()
lastSelectedCell = cell
}
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
print("parent has ", parentVC?.rightDevices.count, " items")
collectionView.reloadData()
}
static func showPopup(parentVC: UIViewController, left: Bool){
//creating a reference for the dialogView controller
if let popupViewController = UIStoryboard(name: "PopUp", bundle: nil).instantiateViewController(withIdentifier: "PopUpController") as? PopUpController {
popupViewController.modalPresentationStyle = .custom
popupViewController.modalTransitionStyle = .crossDissolve
//setting the delegate of the dialog box to the parent viewController
popupViewController.delegate = parentVC as? PopUpDelegate
popupViewController.left = left
parentVC = parentVC as? ViewController
print("showing left popup: ", left)
//presenting the pop up viewController from the parent viewController
parentVC.present(popupViewController, animated: true)
}
}
#IBAction func onConnectPressed(_ sender: Any) {
self.delegate?.connect(device: lastSelectedCell!)
self.dismiss(animated: true, completion: nil)
}
#IBAction func onDismissPressed(_ sender: Any) {
self.dismiss(animated: true, completion: nil)
}
}

Answer 1

Check again leftDevices and rightDevices data passing between ViewController to PopUpController screen and conform delegate and datasources.
collectionView.delegate = self
collectionView.dataSource = self