How to pass @binding variable in uivewcontroller which is hosting a SwiftUI-CodePudding

I am hosting a SwiftUI view inside a view controller. My SwiftUI view has a @Binding data type.

While setting the content view, I need to initialize and set a binding variable.

My SwiftUI View:

struct STSChooseItemsView: View {
    @Environment(\.presentationMode) var presentationMode
    @Binding var selectedImage : UIImage
    var body: some View {
            VStack{
                HStack(){
                    Spacer()
                        .frame(width: 5)
                    Button(action: {
                        presentationMode.wrappedValue.dismiss()
                        self.selectedImage = UIImage()
                    }, label: {
                        Text("X")
                            .fontWeight(.heavy)
                            .foregroundColor(Color.black)
                    })
                    Spacer()
                        .frame(width: 100)
                    Text("CHOOSE ITEMS")
                        .font(.headline)
                        .padding()
                    Spacer()
                        .frame(width: 100)
                }
                .frame(height: 40)
                Spacer()
                Image(uiImage: selectedImage)
                    .frame(width: UIScreen.main.bounds.width - 1, height: 300)
                Spacer()
        }   
    }

My view controller:

import UIKit
import SwiftUI

class STSChooseItemsViewController : UIViewController {
    
    let contentView = UIHostingController(rootView: STSChooseItemsView(selectedImage: **(Please let me know what and how to put data here)**))

    override func viewDidLoad() {
        super.viewDidLoad()
        self.navigationItem.title = "CHOOSE ITEMS"
        addChild(contentView)
        view.addSubview(contentView.view)
        setupConstraints()
        // Do any additional setup after loading the view.
    }

    fileprivate func setupConstraints(){
        contentView.view.translatesAutoresizingMaskIntoConstraints = false
        contentView.view.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
        contentView.view.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
        contentView.view.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
        contentView.view.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
    }
}

I tried initializing the dummy image but I got an error: Cannot use instance member '$myImage' within property initializer; property initializers run before 'self' is available

CodePudding user response：

Try creating a Binding using the init(get:set:) initializer.

class STSChooseItemsViewController: UIViewController {
    
    var image = UIImage()

    lazy var selectedImageBinding = Binding { /// I omitted the argument label using trailing closure shorthand
        return self.image
    } set: { newValue in
        self.image = newValue /// `selectedImageBinding` must be a lazy var to access `self`
    }

    lazy var contentView = UIHostingController(rootView: STSChooseItemsView(selectedImage: selectedImageBinding) /// pass in the binding here

    override func viewDidLoad() {
        super.viewDidLoad()
        self.navigationItem.title = "CHOOSE ITEMS"
        addChild(contentView)
        view.addSubview(contentView.view)
        setupConstraints()
        // Do any additional setup after loading the view.
    }

    fileprivate func setupConstraints() {
        contentView.view.translatesAutoresizingMaskIntoConstraints = false
        contentView.view.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
        contentView.view.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
        contentView.view.leftAnchor.constraint(equalTo: view.leftAnchor).isActive = true
        contentView.view.rightAnchor.constraint(equalTo: view.rightAnchor).isActive = true
    }
}