Passing data in UIViewControllerRepresentable

问题

I'm trying to make a PDFView with UIKit and pass it data from a previous SwiftUI view. The data itself is a string with the name of the file. Somehow, the string is not passed from the UIViewControllerRepresentable to the UIViewController and it stays empty. I really can't find a reason why this is happening. Could you check where I'm wrong? I hope this code is enough.

I'm using NavigationLink(destination: FileViewerWrapper(file: "some string")) {}

import PDFKit
import UIKit
import SwiftUI

let pdfView = PDFView()

class FileViewer: UIViewController {

var file = String()


override func viewDidLoad() {
    super.viewDidLoad()

    print("\n\n\n-----------------------\(file)\n-------------------------------\n\n\n")

    pdfView.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(pdfView)

    pdfView.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor).isActive = true
    pdfView.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor).isActive = true
    pdfView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor).isActive = true
    pdfView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor).isActive = true

    guard let path = Bundle.main.url(forResource: file, withExtension: "pdf", subdirectory: "Files") else { return }

    if let document = PDFDocument(url: path) {
        pdfView.document = document
    }
}
}


struct FileViewerWrapper: UIViewControllerRepresentable {

var file: String

typealias UIViewControllerType = FileViewer


   func makeUIViewController(context: UIViewControllerRepresentableContext<FileViewerWrapper>) -> FileViewerWrapper.UIViewControllerType {
       return FileViewer()
   }

   func updateUIViewController(_ uiViewController: FileViewerWrapper.UIViewControllerType, context: UIViewControllerRepresentableContext<FileViewerWrapper>) {

    uiViewController.file = file
   //When I put print(file) here, it's fine

   }
}

The outcome in is: //----------------------- //-------------------------------

It should be: //----------------------- String //-------------------------------

回答1:

I think I've nailed it:

func makeUIViewController(context: UIViewControllerRepresentableContext<FileViewerWrapper>) -> FileViewerWrapper.UIViewControllerType {
    let uiViewController = FileViewer()
    uiViewController.file = file

       return uiViewController
   }

func updateUIViewController is now empty

回答2:

When you just want to pass the use a separate UIViewControllerRepresentable which will have your UIViewController and then pass the data from View to ViewController.

struct CameraViewControllerRepresentable : UIViewControllerRepresentable {
    typealias UIViewControllerType = CameraViewController
    var patientObject: PatientObj

    public func makeUIViewController(context: UIViewControllerRepresentableContext<CameraViewControllerRepresentable>) -> CameraViewController {
        let cameraVC = UIStoryboard(name: "Camera", bundle: nil).instantiateViewController(identifier: String(describing: CameraViewController.self)) as! CameraViewController
        cameraVC.patientObj = patientObject
        return cameraVC


       }

    func updateUIViewController(_ uiViewController: CameraViewController, context: UIViewControllerRepresentableContext<CameraViewControllerRepresentable>) {

    }

}

来源：https://stackoverflow.com/questions/58352016/passing-data-in-uiviewcontrollerrepresentable

标签

xcode

swiftui

pdfkit