Use SwiftUI in Action Extension

ActionViewController.swift

import UIKit
import MobileCoreServices
import SwiftUI

class ActionViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
    
        // Get the item[s] we're handling from the extension context.
        
        // For example, look for an image and place it into an image view.
        // Replace this with something appropriate for the type[s] your extension supports.
        for item in self.extensionContext!.inputItems as! [NSExtensionItem] {
            for provider in item.attachments! {
               if provider.hasItemConformingToTypeIdentifier("public.url") {
                    provider.loadItem(forTypeIdentifier: "public.url", options: nil, completionHandler: { (url, error) -> Void in
                        if let shareURL = url as? NSURL {
                            let parsedUrl = URL(string: shareURL.absoluteString!)!
                            print("find url = ", parsedUrl)
                            
                            // build the SwiftUI view, wrap it in a UIHostingController then send to the main thread to update the UI
                            let contentView = SecondView(url: parsedUrl.absoluteString, clickedDone: self.done)
                            let viewController = UIHostingController(rootView: contentView)
                            
                            DispatchQueue.main.async {
                                self.present(viewController, animated: true)
                            }

                        }
                    })
                }
            }
        }
    }

    func done() {
        // Return any edited content to the host app.
        // This template doesn't do anything, so we just echo the passed in items.
        self.extensionContext!.completeRequest(returningItems: self.extensionContext!.inputItems, completionHandler: nil)
    }

}

SecondView.swift

import SwiftUI

struct SecondView: View {
    @State var url: String
    var clickedDone: () -> Void

    var body: some View {
      VStack {
        Button("Done") {
            self.clickedDone()
        }
        Text(url).font(.system(size: 36))
        Text("Loaded by SecondView").font(.system(size: 14))
      }
    }
}