Navigate to UIViewController from SwiftUI

Question

My initial view is built using SwiftUI.

I'd like to transition to a UIViewController from this & call a method that may alter the design, an example is hiding an IBOutlet.

Here's what I am doing currently:

@available(iOS 13.0, *)
struct DetailViewControllerWrapper: UIViewControllerRepresentable {
    typealias UIViewControllerType = DetailViewController

    func makeUIViewController(context: UIViewControllerRepresentableContext<DetailViewControllerWrapper>) -> DetailViewControllerWrapper.UIViewControllerType {

        let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
        let detailViewController: DetailViewController = mainStoryboard.instantiateViewController(withIdentifier: "detailViewController") as! DetailViewController
        detailViewController.someMethod()
        return detailViewController
    }

    func updateUIViewController(_ uiViewController: DetailViewControllerWrapper.UIViewControllerType, context: UIViewControllerRepresentableContext<DetailViewControllerWrapper>) {
        //
    }
}

This is pushing to my DetailViewController but I'm getting a Unexpectedly found nil while implicitly unwrapping an Optional value error.

Any advice on navigating from SwiftUI to UIKit / UIViewController?

Answer 1

Part of working with UIViewRepresentable is calling a required func called makeCoordinator() as cited here in the docs. Apple also has a tutorial on how to interface with UIKit which you can find here . Another tutorial from Paul Hudson here might also be useful to you. I used the coordinator pattern from it to provide an UIImagePickerController in a SwiftUI app I'm working on. That code is below. You'll notice the nested class which provides the functionality I need for the UIImagePickerController , in your case I believe you just need to call the DetailViewController. I hope this helps. -Dan

import SwiftUI

class PhotosData: NSObject, Codable {
    var image: String?

    init(image: String) {
        self.image = image
      }
    }

struct ImagePicker: UIViewControllerRepresentable {
    @Environment(\.presentationMode) var presentationMode
    @Binding var image: UIImage?

class Coordinator: NSObject, UINavigationControllerDelegate, UIImagePickerControllerDelegate {
    let parent: ImagePicker

    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
        if let uiImage = info[.originalImage] as? UIImage {
            parent.image = uiImage
        }
        parent.presentationMode.wrappedValue.dismiss()
    }

    init(_ parent: ImagePicker) {
        self.parent = parent
        }
    }

    func makeUIViewController(context: UIViewControllerRepresentableContext<ImagePicker>) -> UIImagePickerController {
        let picker = UIImagePickerController()
        picker.delegate = context.coordinator
        return picker
    }

    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }

    func updateUIViewController(_ uiViewController: UIImagePickerController, context: UIViewControllerRepresentableContext<ImagePicker>) { 
    /*Required. Not used*/ 
        }

}