How to incorporate a UISearchController into SwiftUI NavigationView by using UINavigationController's searchController property?

Question

I am trying to create a SwiftUI view where I have a NavigationView that wraps a custom MapView (which wraps MKMapView), but, with very minimal success, I cannot seem to integrate a search controller into the NavigationView, unlike how you would easily be able to with a UINavigationController. I have tried to create my own custom NavigationView with some success, but I don't particularly want to recreate something of that scope in order to add one piece of functionality (unless that's the only solution).

Realistically, I mainly want to know if it is even possible to do what I'm asking, or if that is something I would have to implement myself, and if so, how?

Thanks!

import SwiftUI

struct CustomNavigationController<Content: View>: UIViewControllerRepresentable {
    var title: String

    var content: () -> Content

    init(title: String, @ViewBuilder content: @escaping () -> Content) {
        self.content = content
        self.title = title
    }

    func makeUIViewController(context: UIViewControllerRepresentableContext<CustomNavigationController<Content>>) -> UINavigationController {
        let contents = UIHostingController(rootView: self.content())
        let nc = UINavigationController(rootViewController: contents)
        nc.navigationBar.prefersLargeTitles = true

        return nc
    }

    func updateUIViewController(_ uiViewController: UINavigationController, context: UIViewControllerRepresentableContext<CustomNavigationController<Content>>) {
        uiViewController.navigationBar.topItem?.title = title
        let results = SearchResultsController()
        let sc = UISearchController(searchResultsController: results)
        sc.searchResultsUpdater = results
        sc.hidesNavigationBarDuringPresentation = false
        sc.obscuresBackgroundDuringPresentation = false
        uiViewController.navigationBar.topItem?.searchController = sc
    }
}

import UIKit
import MapKit

class SearchResultsController: UITableViewController {
    let reuseIdentifier = "Cell"

    var results: [MKMapItem] = []

    init() {
        super.init(nibName: nil, bundle: nil)
    }

    required init?(coder: NSCoder) {
        super.init(coder: coder)
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        tableView.register(UITableViewCell.self, forCellReuseIdentifier: reuseIdentifier)
    }

    // MARK: - Table view data source
    override func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return results.count
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: reuseIdentifier, for: indexPath)

        let selected = results[indexPath.row].placemark

        print(selected)

        cell.textLabel?.text = selected.title
        cell.detailTextLabel?.text = selected.title

        return cell
    }

    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        print("Clicked")
    }
}

extension SearchResultsController : UISearchResultsUpdating {
    func updateSearchResults(for searchController: UISearchController) {
        guard let searchBarText = searchController.searchBar.text else { return }

        let request = MKLocalSearch.Request()
        request.naturalLanguageQuery = searchBarText
        request.region = .init()

        let search = MKLocalSearch(request: request)

        search.start(completionHandler: { response, error in
            guard let response = response else { return }

            self.results = response.mapItems
            self.tableView.reloadData()
        })
    }
}

That is the code for my custom UINavigationController to make something similar to a NavigationView. This works and displays the search bar in the navigation bar, but it isn't ideal nor do I feel like it is best practice.

Answer 1

I was able to get this working without using UINavigationController in a UIViewControllerRepresentable. In fact, in my own experiments in answering this question I found that to be a quite error prone method when views get updated.

The technique here is similar to that question: Use a dummy UIViewController in order to configure your navigation.

struct ContentView: View {
    var body: some View {
        NavigationView {
            NavigationLink(destination: Text("Bye")) {
                Text("Hi")
                    .background(SearchControllerSetup())
                    .navigationBarTitle("Hello", displayMode: .inline)
            }
        }
    }
}

struct SearchControllerSetup: UIViewControllerRepresentable {
    typealias UIViewControllerType = UIViewController

    func makeCoordinator() -> SearchCoordinator {
        return SearchCoordinator()
    }

    func makeUIViewController(context: Context) -> UIViewController {
        return UIViewController()
    }

    func updateUIViewController(_ uiViewController: UIViewController, context: Context) {
        // This will be called multiple times, including during the push of a new view controller
        if let vc = uiViewController.parent {
            vc.navigationItem.searchController = context.coordinator.search
        }
    }

}

class SearchCoordinator: NSObject {

    let updater = SearchResultsUpdater()
    lazy var search: UISearchController = {
        let search = UISearchController(searchResultsController: nil)
        search.searchResultsUpdater = self.updater
        search.obscuresBackgroundDuringPresentation = false
        search.searchBar.placeholder = "Type something"
        return search
    }()
}

class SearchResultsUpdater: NSObject, UISearchResultsUpdating {
    func updateSearchResults(for searchController: UISearchController) {
        guard let text = searchController.searchBar.text else { return }
        print(text)
    }
}

Results:

Answer 2

(EDIT) iOS 15:

iOS 15 added the new property .searchable(). You should probably use that instead.

Original:

If anyone is still looking, I just made a package to deal with this really cleanly, inspired by @arsenius's answer

I'm also including the full relevant source code here for those who dislike links or just want to copy/paste.

Extension:

// Copyright © 2020 thislooksfun
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the “Software”), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

import SwiftUI
import Combine

public extension View {
    public func navigationBarSearch(_ searchText: Binding<String>) -> some View {
        return overlay(SearchBar(text: searchText).frame(width: 0, height: 0))
    }
}

fileprivate struct SearchBar: UIViewControllerRepresentable {
    @Binding
    var text: String
    
    init(text: Binding<String>) {
        self._text = text
    }
    
    func makeUIViewController(context: Context) -> SearchBarWrapperController {
        return SearchBarWrapperController()
    }
    
    func updateUIViewController(_ controller: SearchBarWrapperController, context: Context) {
        controller.searchController = context.coordinator.searchController
    }
    
    func makeCoordinator() -> Coordinator {
        return Coordinator(text: $text)
    }
    
    class Coordinator: NSObject, UISearchResultsUpdating {
        @Binding
        var text: String
        let searchController: UISearchController
        
        private var subscription: AnyCancellable?
        
        init(text: Binding<String>) {
            self._text = text
            self.searchController = UISearchController(searchResultsController: nil)
            
            super.init()
            
            searchController.searchResultsUpdater = self
            searchController.hidesNavigationBarDuringPresentation = true
            searchController.obscuresBackgroundDuringPresentation = false
            
            self.searchController.searchBar.text = self.text
            self.subscription = self.text.publisher.sink { _ in
                self.searchController.searchBar.text = self.text
            }
        }
        
        deinit {
            self.subscription?.cancel()
        }
        
        func updateSearchResults(for searchController: UISearchController) {
            guard let text = searchController.searchBar.text else { return }
            self.text = text
        }
    }
    
    class SearchBarWrapperController: UIViewController {
        var searchController: UISearchController? {
            didSet {
                self.parent?.navigationItem.searchController = searchController
            }
        }
        
        override func viewWillAppear(_ animated: Bool) {
            self.parent?.navigationItem.searchController = searchController
        }
        override func viewDidAppear(_ animated: Bool) {
            self.parent?.navigationItem.searchController = searchController
        }
    }
}

Usage:

import SwiftlySearch

struct MRE: View {
  let items: [String]

  @State
  var searchText = ""

  var body: some View {
    NavigationView {
      List(items.filter { $0.localizedStandardContains(searchText) }) { item in
        Text(item)
      }.navigationBarSearch(self.$searchText)
    }
  }
}