demoPulltoRefreshSwiftUI.swift

import SwiftUI
import UIKit

struct Result: Identifiable {
    var id = UUID()
    var value: String
}


class RefreshableObject: ObservableObject {
    let id = UUID()
    @Published var items: [Result] = [Result(value: "Binding"),
                                      Result(value: "ObservableObject"),
                                      Result(value: "Published")]

    let refreshControl: UIRefreshControl

    init() {
        refreshControl = UIRefreshControl()
        refreshControl.addTarget(self, action:
            #selector(self.handleRefreshControl),
                                      for: .valueChanged)
    }

    @objc func handleRefreshControl(sender: UIRefreshControl) {
           DispatchQueue.main.asyncAfter(deadline: .now() + 1.5) {  [weak self] in
                sender.endRefreshing()
                self?.items = [Result(value:"new"), Result(value:"data"), Result(value:"after"), Result(value:"refresh")]
           }
    }
}



struct ContentView: View {

    @ObservedObject var refreshableObject = RefreshableObject()
    var body: some View {
            NavigationView {
                Form {
                    Section(footer: UIKitView.init { (tableView) in
                        
                        if tableView.refreshControl == nil  {
                           tableView.refreshControl = self.refreshableObject.refreshControl
                        }
                    }){
                        ForEach(refreshableObject.items) { result in
                            Text(result.value)
                        }
                    }

                }
                    .navigationBarTitle("Nav bar")

            }
    }
}

final class UIKitView : UIViewRepresentable {
    let callback: (UITableView) -> Void
    
    init(leafViewCB: @escaping ((UITableView) -> Void)) {
        callback = leafViewCB
    }
    
    func makeUIView(context: Context) -> UIView  {
        let view = UIView.init(frame: CGRect(x: CGFloat.leastNormalMagnitude,
                                             y: CGFloat.leastNormalMagnitude,
                                             width: CGFloat.leastNormalMagnitude,
                                             height: CGFloat.leastNormalMagnitude))
        view.backgroundColor = .clear
        return view
    }
         
    func updateUIView(_ uiView: UIView, context: Context) {
        if let superView = uiView.superview {
            superView.backgroundColor = uiView.backgroundColor
        }
        
        if let tableView = uiView.next(UITableView.self) {
            callback(tableView)
        }
    }
}

extension UIResponder {
    func next<T: UIResponder>(_ type: T.Type) -> T? {
        return next as? T ?? next?.next(type)
    }
}