Refresh Control for iOS 14 or less

RefreshControlPOC.swift

import SwiftUI
import Introspect
import UIKit

struct ContentView: View {
    @ObservedObject private var viewModel = ViewModel()

    var body: some View {
        NavigationView {
            Group {
                if viewModel.isLoading {
                    Text("Loading...")
                } else {
                    ScrollView {
                        VStack {
                            ForEach(viewModel.items, id: \.self) { item in
                                Text(item)
                                    .padding()
                            }
                        }
                    }
                    .onPullToRefresh {
                        self.viewModel.fetchItems()
                    }
                }
            }
            .navigationBarTitle("My List")
            .onAppear {
                self.viewModel.fetchItems()
            }
        }
    }
}

final class RefreshableContextController: ObservableObject {
    private var onValueChanged: (@Sendable (_ refreshControl: UIRefreshControl) async -> Void)?
    
    func setupRefreshControl(for scrollView: UIScrollView, onValueChanged: @escaping @Sendable (_ refreshControl: UIRefreshControl) async -> Void) {
        let refreshControl = UIRefreshControl()
        refreshControl.addTarget(
            self,
            action: #selector(self.onValueChanged(sender:)),
            for: .valueChanged
        )
        scrollView.refreshControl = refreshControl
        self.onValueChanged = onValueChanged
    }
    
    @objc private func onValueChanged(sender: UIRefreshControl) {
        Task { @MainActor in
            await onValueChanged?(sender)
        }
    }
}

struct RefreshableContext<Content: View>: View {
    @StateObject var controller = RefreshableContextController()
    let content: () -> Content
    let onRefresh: @Sendable () async -> Void
    
    init(
        content: @escaping () -> Content,
        onRefresh:  @escaping @Sendable () async -> Void
    ) {
        self.content = content
        self.onRefresh = onRefresh
    }
    
    var body: some View {
        content()
            .introspectScrollView { scrollView in
                controller.setupRefreshControl(for: scrollView) { _ in
                    await onRefresh()
                }
            }
    }
}

extension View {
    @ViewBuilder
    func onPullToRefresh(action: @escaping () -> Void) -> some View {
        self.onPullToRefreshAsync { action() }
    }
    
    @ViewBuilder
    func onPullToRefreshAsync(action: @escaping @Sendable () async -> Void) -> some View {
        if #available(iOS 15.0, *) {
            self.refreshable(action: action)
        } else {
            RefreshableContext(
                content: { self },
                onRefresh: action
            )
        }
    }
}

class ViewModel: ObservableObject {
    @Published var items = [String]()
    @Published var isLoading = false

    func fetchItems() {
        isLoading = true
        DispatchQueue.main.asyncAfter(deadline: .now()+1) {
            self.items = (0..<10).map { "Item \($0)" }
            self.isLoading = false
        }
    }
}