如何通过 SwiftUI 按钮在 UIViewController 中执行功能？

Question

在下面的代码中，我试图弄清楚如何使用SwiftUI 按钮执行savePhoto 函数。这实际上是我试图解决的问题的简化版本，但仍然无法弄清楚。我在ContentView 中创建的按钮是我想象的解决问题的方法，但由于 SwiftUI 结构，我似乎找不到解决方法。

这是我的 SwiftUI 视图：

struct ContentView: View {
    var body: some View {
        ZStack{
            AnotherControllerView()
            Button(action: { AnotherControllerView.savePhoto() }){
                Text("Save Photo")
            }
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

还有我的集成 UIViewController：

import Foundation
import SwiftUI
import UIKit

struct AnotherControllerView : UIViewControllerRepresentable {

    typealias UIViewControllerType = AnotherController

    func makeCoordinator() -> AnotherControllerView.Coordinator {
        Coordinator(self)
    }

    func makeUIViewController(context: UIViewControllerRepresentableContext<AnotherControllerView>) -> AnotherController {

        return AnotherController()
    }

    func updateUIViewController(_ uiViewController: AnotherController, context: UIViewControllerRepresentableContext<AnotherControllerView>) {

    }


    class Coordinator : NSObject {
        var parent : AnotherControllerView
        init(_ viewController : AnotherControllerView){
            self.parent = viewController
        }
    }
}

class AnotherController : UIViewController {


    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = UIColor.blue
    }

    func savePhoto(){

        let alert = UIAlertController(title: "Save Photo to Camera Roll", message: "Would you like to save your drawing to the camera roll?", preferredStyle: .alert)
        alert.addAction(UIAlertAction(title: "Cancel", style: .default, handler: nil))
        alert.addAction(UIAlertAction(title: "Save", style: .default, handler: someHandler))
        self.present(alert, animated: true)
    }

    func someHandler(alert: UIAlertAction!) {
        print("Handler executed")
    }
}

Answer 1

你好要控制 UIViewController 我们需要在 View 和 UIViewControllerRepresentable 之间创建一个绑定 让我们用代码解释一下： 首先，您需要在AnotherControllerView 中声明一个带有@Binding 注释的新变量

会是这样的：

struct AnotherControllerView : UIViewControllerRepresentable {

    @Binding var isShown: Bool
    typealias UIViewControllerType = AnotherController

    func makeCoordinator() -> AnotherControllerView.Coordinator {
        Coordinator()
    }

    func makeUIViewController(context: UIViewControllerRepresentableContext<AnotherControllerView>) -> AnotherController {

        return AnotherController(isShown: $isShown)
    }

    func updateUIViewController(_ controller: AnotherController, context: UIViewControllerRepresentableContext<AnotherControllerView>) {
        if(self.isShown){
            controller.savePhoto()
        }
    }


    class Coordinator : NSObject {

    }
}

为此，我们在updateUIViewController 中实现逻辑

class AnotherController : UIViewController {

     @Binding var isShown: Bool

    init(isShown: Binding<Bool>) {
        _isShown = isShown
        super.init(nibName: nil, bundle: nil)

    }



    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }


    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = UIColor.blue
    }

    func savePhoto(){

        let alert = UIAlertController(title: "Save Photo to Camera Roll", message: "Would you like to save your drawing to the camera roll?", preferredStyle: .alert)
        alert.addAction(UIAlertAction(title: "Cancel", style: .default, handler: cancelAlert))
        alert.addAction(UIAlertAction(title: "Save", style: .default, handler: someHandler))
        self.present(alert, animated: true)
    }

    func cancelAlert(alert: UIAlertAction!) {
        self.isShown = false
    }

    func someHandler(alert: UIAlertAction!) {
        print("Handler executed")
    }
}

如果你想捕捉图像，让我告诉你我是如何实现的：

struct CaptureImageView {
    @Binding var isShown: Bool
    @Binding var image: Image?
    var sourceType: UIImagePickerController.SourceType

    func makeCoordinator() -> Coordinator {
        return Coordinator(isShown: $isShown, image: $image)
    }
}

extension CaptureImageView: UIViewControllerRepresentable {
    func makeUIViewController(context: UIViewControllerRepresentableContext<CaptureImageView>) -> UIImagePickerController {
        let picker = UIImagePickerController()
        picker.delegate = context.coordinator
        picker.sourceType = sourceType
        return picker
    }

    func updateUIViewController(_ uiViewController: UIImagePickerController, context: UIViewControllerRepresentableContext<CaptureImageView>) {

    }

    class Coordinator: NSObject, UINavigationControllerDelegate, UIImagePickerControllerDelegate {
        @Binding var isCoordindatorShown: Bool
        @Binding var imageInCoordinator: Image?

        init(isShown: Binding<Bool>, image: Binding<Image?>) {
            _isCoordindatorShown = isShown
            _imageInCoordinator = image
        }

        func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
            guard let unwrapImage = info[UIImagePickerController.InfoKey.originalImage] as? UIImage else {return}
            imageInCoordinator = Image(uiImage: unwrapImage)
            isCoordindatorShown = false
        }

        func imagePickerControllerDidCancel(_ picker: UIImagePickerController) {
            isCoordindatorShown = false
        }
    }

}

我只是在正文中调用：

CaptureImageView(isShown: $showCaptureImageView, image: $imageCaptured, sourceType: importSourceType)

Answer 2

如果 AnotherControllerView 很大并且您很少在新版本中使用它，您可以考虑使用更简单的解决方法。

        struct ContentAnotherControllerView: View {

            let   anotherControllerView = AnotherControllerView()

            var body: some View {
                ZStack{
                    anotherControllerView
                    Button(action: { self.anotherControllerView.savePhoto() }){
                        Text("Save Photo")
                    }
                }
            }
        }



     struct AnotherControllerView : UIViewControllerRepresentable {

     typealias UIViewControllerType = AnotherController

     var savePhotoDelegate: AnotherController? = AnotherController()

    func savePhoto(){
         savePhotoDelegate?.savePhoto()
     }


     func makeUIViewController(context:   UIViewControllerRepresentableContext<AnotherControllerView>) -> AnotherController {

    if let savePhotoDelegate = savePhotoDelegate{
        return savePhotoDelegate
    }
    return AnotherController()
    }
   ....}

这种方法只是提醒我们一个视图可以在某些情况下重用。由于 UIView 桥不是纯 SwiftUI 域，你可以试试这种方式。