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Hi, I'm an experienced developer on Apple platforms (having worked on iOS/tvOS projects for more than 10 years now). However, I've only worked on applications, or simple games which didn't require more than using UIKit or SwiftUI. Now, I'd like to start a new project, recreating an old game on tvOS with 3D graphics. This is not a project I plan to release, only a simple personal challenge. I'm torn with starting this project with either SceneKit, or Unity. On one hand, I love Apple frameworks and tools, so I guess I could easily progress with SceneKit. Also, I don't know Unity very well, but even if it's a simple project, I've seen that there are several restrictions for free plans (no custom splash screen, etc). On the other hand, I've read several threads (i.e. this one) making it look like that SceneKit isn't going anywhere, and clearly recommending Unity due to the fact that its documentation is way better, and the game more easily portable to other platforms. Also, if I'm going to learn something new, maybe I could learn more with Unity (using a completely different platform, software and language) than I would with SceneKit and Swift stuff. What's your opinion about this? Thanks!

I have a UIViewController that presents a UIDocumentPicker to pick PDF files, and contains a UICollectionView that displays them (each cell contains a PDFView to do so). Here is the code: import MobileCoreServices; import PDFKit; import UIKit class ViewController: UIViewController { var urls: [URL] = [] @IBOutlet weak var collectionView: UICollectionView! @IBAction func pickFile() { DispatchQueue.main.async { let documentPicker = UIDocumentPickerViewController(documentTypes: [kUTTypePDF as String], in: .import) documentPicker.delegate = self documentPicker.modalPresentationStyle = .formSheet self.present(documentPicker, animated: true, completion: nil) } } override func viewDidLoad() { collectionView.register(UINib(nibName: PDFCollectionViewCell.identifier, bundle: .main), forCellWithReuseIdentifier: PDFCollectionViewCell.identifier) } init() { super.init(nibName: "ViewController", bundle: .main) } required init?(coder: NSCoder) { fatalError() } } extension ViewController: UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout { func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell { let cell = collectionView.dequeueReusableCell(withReuseIdentifier: PDFCollectionViewCell.identifier, for: indexPath) as! PDFCollectionViewCell cell.pdfView.document = PDFDocument(url: urls[indexPath.row]) return cell } func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int { return urls.count } func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize { CGSize(width: 150, height: 150) } } extension ViewController: UIDocumentPickerDelegate { // MARK: PDF Picker Delegate func documentPickerWasCancelled(_ controller: UIDocumentPickerViewController) { controller.dismiss(animated: true, completion: nil) } func documentPicker(_ controller: UIDocumentPickerViewController, didPickDocumentsAt urls: [URL]) { controller.dismiss(animated: true, completion: { DispatchQueue.main.async { self.urls.append(contentsOf: urls) self.collectionView.reloadData() } }) } } class PDFCollectionViewCell: UICollectionViewCell { static let identifier = "PDFCollectionViewCell" @IBOutlet weak var pdfView: PDFView! { didSet { setPdfViewUI() } } func setPdfViewUI() { pdfView.displayMode = .singlePage pdfView.autoScales = true pdfView.displayDirection = .vertical pdfView.isUserInteractionEnabled = false } } Now, for some reason, the collectionView.reloadData() actually only works one time in two. It works the first time, then the second time nothing happens, then the third time the collection view is updated again with the three expected elements... I realized that even if I'm calling reloadData(), the dataSource and delegate methods (numberOfItems/cellForItem) are not getting called when this happens. Any idea of what is happening? Am I doing something wrong? Thank you for your help!