UIScrollViewWrapper.swift

//
//  UIScrollViewWrapper.swift
//
//  Created by Justin Schwartz on 12/29/20.
//

import SwiftUI
import UIKit

struct UIScrollViewWrapper<Content: View>: UIViewControllerRepresentable {
    var content: () -> Content
    
    func makeUIViewController(context: Context) -> UIScrollViewViewController {
        let vc = UIScrollViewViewController()
        vc.hostingController.rootView = AnyView(self.content())
        return vc
    }
    
    func updateUIViewController(_ viewController: UIScrollViewViewController, context: Context) {
        viewController.hostingController.rootView = AnyView(self.content())
    }
}

class UIScrollViewViewController: UIViewController {
    lazy var scrollView: UIScrollView = {
        let view = UIScrollView()
        view.showsVerticalScrollIndicator = false
        view.alwaysBounceVertical = true        
        return view
    }()
    
    let refreshControl = UIRefreshControl()    
    var hostingController: UIHostingController<AnyView> = UIHostingController(rootView: AnyView(EmptyView()))
    
    override func viewDidLoad() {
        super.viewDidLoad()
        refreshControl.addTarget(self, action: #selector(didPullToRefresh), for: .valueChanged)
        
        self.hostingController.willMove(toParent: self)
        self.hostingController.view.backgroundColor = .clear
        self.hostingController.didMove(toParent: self)
        
        self.view.addSubview(self.scrollView)
        self.scrollView.addSubview(refreshControl)
        self.scrollView.addSubview(self.hostingController.view)
        
        self.pinEdges(of: self.scrollView, to: self.view)
        self.pinEdges(of: self.hostingController.view, to: self.scrollView)
    }
    
    @objc func didPullToRefresh() {
        // Update your content…
        
        // Dismiss the refresh control.
        DispatchQueue.main.async {
            self.refreshControl.endRefreshing()
        }
    }
    
    func pinEdges(of viewA: UIView, to viewB: UIView) {
        viewA.translatesAutoresizingMaskIntoConstraints = false
        viewB.addConstraints([
            viewA.leadingAnchor.constraint(equalTo: viewB.leadingAnchor),
            viewA.trailingAnchor.constraint(equalTo: viewB.trailingAnchor),
            viewA.topAnchor.constraint(equalTo: viewB.topAnchor),
            viewA.bottomAnchor.constraint(equalTo: viewB.bottomAnchor),
        ])
    }
}