SwiftUI UISearchController searchResultsController 导航堆栈问题

Question

我有为 SwiftUI 制作的 UISearchController

UIViewControllerRepresentable

，如下：

struct SearchViewController<Content: View>: UIViewControllerRepresentable {
    var content: () -> Content
    let searchResultsView = SearchResultsView()

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

    func makeUIViewController(context: Context) -> UINavigationController {

        let rootViewController = UIHostingController(rootView: content())
        let navigationController = UINavigationController(rootViewController: rootViewController)
        let searchResultsController = UIHostingController(rootView: searchResultsView)

        // Set nav properties
        navigationController.navigationBar.prefersLargeTitles = true
        navigationController.definesPresentationContext = true

        // Create search controller
        let searchController = UISearchController(searchResultsController: searchResultsController)
        searchController.searchBar.autocapitalizationType = .none
        searchController.delegate =  context.coordinator
        searchController.searchBar.delegate = context.coordinator // Monitor when the search button is tapped.

        // Create default view
        rootViewController.navigationItem.searchController = searchController
        rootViewController.title = "Search"

        return navigationController
    }

    func updateUIViewController(_ navigationController: UINavigationController, context: UIViewControllerRepresentableContext<SearchViewController>) {
        //
    }
}

这有效，并在用户搜索时显示

searchResultsController

。然而，

searchResultsController

似乎不知道它是导航上下文/堆栈，所以我无法从

searchResultsController

中的列表视图进行导航。

是否可以将其构造为允许从

searchResultsController

进行导航，或者这是当前 SwiftUI 的限制。

非常感谢任何建议！

Answer 1

我最近也需要在我的应用程序中实现此功能（搜索栏如导航栏）。看你的片段真的给了 m2 很大的启发！ 首先感谢！

向您、ula1990、Lorenzo Boaro和V8tr学习后，我实现了自己的。

我将

searchResultsController

设置为

nil

（由于其中不可点击的导航链接，所以我将其设置为nil）。

代码：

struct SearchController<Result: View>: UIViewControllerRepresentable {
    @Binding var searchText: String
    private var content: (_ searchText:String)->Result
    
    private var searchBarPlaceholder: String
    

    init(_ searchBarPlaceholder: String = "", searchedText: Binding<String>,
         resultView: @escaping (_ searchText:String) -> Result) {
        self.content = resultView
        self._searchText = searchedText
        self.searchBarPlaceholder = searchBarPlaceholder
    }
    func makeUIViewController(context: Context) -> UINavigationController {
        let contentViewController = UIHostingController(rootView: SearchResultView(result: $searchText, content: content))
        let navigationController = UINavigationController(rootViewController: contentViewController)
        
        let searchController = UISearchController(searchResultsController: nil)
        searchController.searchResultsUpdater = context.coordinator
        searchController.obscuresBackgroundDuringPresentation = false // for results
        searchController.searchBar.placeholder = searchBarPlaceholder
        
        contentViewController.title = "\\(Title)" // for customization
        contentViewController.navigationItem.searchController = searchController
        contentViewController.navigationItem.hidesSearchBarWhenScrolling = true
        contentViewController.definesPresentationContext = true
        
        searchController.searchBar.delegate = context.coordinator
        
        return navigationController
    }
    
    func updateUIViewController(_ uiViewController: UINavigationController, context: UIViewControllerRepresentableContext<SearchController>) {
        // 
        
    }
}
extension SearchController {
    func makeCoordinator() -> SearchController<Result>.Coordinator {
        Coordinator(self)
    }
    class Coordinator: NSObject, UISearchResultsUpdating, UISearchBarDelegate {
        var parent: SearchController
        init(_ parent: SearchController){self.parent = parent}
        
        // MARK: - UISearchResultsUpdating
        func updateSearchResults(for searchController: UISearchController) {
            self.parent.searchText = searchController.searchBar.text!
        }
        
        // MARK: - UISearchBarDelegate
        func searchBarCancelButtonClicked(_ searchBar: UISearchBar) {
            self.parent.searchText = ""
        }

        func searchBarShouldBeginEditing(_ searchBar: UISearchBar) -> Bool {
            self.parent.searchText = ""
            return true
        }
    }
}

// "nofity" the result content about the searchText
struct SearchResultView<Content: View>: View { 
    @Binding var searchText: String
    private var content: (_ searchText:String)->Content
    init(result searchText: Binding<String>, @ViewBuilder content: @escaping (_ searchText:String) -> Content) {
        self._searchText = searchText
        self.content = content
    }
    var body: some View {
        content(searchText)
    }
}

我不知道这是否是你想要的，但再次感谢！.

Answer 2

（编辑）iOS 15+：

iOS 15 添加了新属性

.searchable()

（这里是关于如何使用它的官方指南）。您应该改用它，除非您仍然需要以 iOS 14 或更低版本为目标。

原文：

我刚刚制作了一个包，可能会解决这个问题。它与 @EthanMengoreo 的答案类似，但（在我看来）具有更像 SwiftUI 的语法。

我还为那些不喜欢链接或只想复制/粘贴的人提供了完整的相关源代码。

扩展名：

// 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
        }
    }
}

用途：

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)
    }
  }
}