gistfile1.txt

import Combine
import QuickLook

class PreviewControllerHolder: UIViewController {
    var cancellables = Set<AnyCancellable>()
    var url: URL
    var startEditing: PassthroughSubject<Void, Never>
    var endEditing: () -> Void
    
    var previewController = QLPreviewController()
    
    init(url: URL, startEditing: PassthroughSubject<Void, Never>, endEditing: @escaping () -> Void) {
        self.url = url
        self.startEditing = startEditing
        self.endEditing = endEditing
        super.init(nibName: nil, bundle: nil)
    }
    
    required init?(coder: NSCoder) {
        url = URL(fileURLWithPath: "")
        startEditing = PassthroughSubject<Void, Never>()
        endEditing = { }
        super.init(coder: coder)
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        view.alpha = 0
        
        previewController.delegate = self
        previewController.dataSource = self
        
        startEditing
            .sink { [weak self] in
                guard let self = self else { return }
                self.present(self.previewController, animated: true, completion: nil)
        }
        .store(in: &cancellables)
    }
}

extension PreviewControllerHolder: QLPreviewControllerDataSource {
    func numberOfPreviewItems(in controller: QLPreviewController) -> Int {
        1
    }
    
    func previewController(_ controller: QLPreviewController, previewItemAt index: Int) -> QLPreviewItem {
        url as QLPreviewItem
    }
}

extension PreviewControllerHolder: QLPreviewControllerDelegate {
    func previewController(_ controller: QLPreviewController, editingModeFor previewItem: QLPreviewItem) -> QLPreviewItemEditingMode {
        .updateContents
    }
    
    func previewControllerDidDismiss(_ controller: QLPreviewController) {
        endEditing()
    }
}