CODEWITHSUNDEEP
iosswiftswiftui
aheze
aheze

Reputation: 30336

UIKit UIViewController that passes a Binding to a SwiftUI View

I'm trying to make a SwiftUI View available in UIKit. Currently, there's a Binding<Bool> that I use for dismissing/presenting DetailView. Here's the working code:

struct ContentView: View {
    @State var presentingModal = false
    var body: some View {
        Button("Present") { self.presentingModal = true } /// tap button to present detail sheet
        .sheet(isPresented: $presentingModal) {
            DetailView(isPresentedBinding: $presentingModal) /// pass in the binding
        }
    }
}

struct DetailView: View {
    var isPresented: Binding<Bool>? /// it's an optional so I do this instead of `@Binding var isPresented: Bool`
    var body: some View {
        Button("Done") { isPresented?.wrappedValue = false } /// tap the "Done" button to dismiss
    }
}

When you press the "Done" button, it sets isPresented to false, which dismisses the sheet. Now I want to present DetailView from a UIViewController. This is what I have so far:

class ViewController: UIViewController {
    @IBAction func presentButtonPressed(_ sender: Any) {
        let detailViewController = DetailView_UIKit()
        self.present(detailViewController, animated: true, completion: nil)
    }
}

/// wrap DetailView in a ViewController so it's easier to present
class DetailView_UIKit: UIViewController {
    
    init() {
        super.init(nibName: nil, bundle: nil)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func loadView() {
        
        view = UIView()

        /// Host the `DetailView`
        let detailViewController = UIHostingController(
            rootView: DetailView() /// I need to pass a Binding in here!
        )
        
        self.addChild(detailViewController)
        view.addSubview(detailViewController.view)
        detailViewController.view.frame = view.bounds
        detailViewController.view.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        detailViewController.didMove(toParent: self)
    }
    
    /// I want to call this function too
    func dismissThisViewController() {
        self.dismiss(animated: true, completion: nil)
    }
}

This works, but the "Done" button doesn't do anything... the Binding is still nil because I haven't assigned it to anything. How can I create some sort of @State property inside DetailView_UIKit so that I can pass it into DetailView? I would like dismissThisViewController to be called when that property is set to false. Or maybe creating an @State property isn't the right approach, I'm not sure.

SwiftUI flow:

ContentView (present)→ DetailView
        ◟________________◞
             Binding

UIKit flow:

ViewController (present)→ DetailView_UIKit → DetailView
                               ◟________________◞
                          Binding? Not sure what to put

Thanks for your help!

Upvotes: 17

Views: 8992

Answers (1)

aheze
aheze

Reputation: 30336

So it turns out you can't use a Binding between a UIViewController and View.

In the end, I just made an optional closure in DetailView.

  • If I present DetailView_UIKit, I will assign the closure to a dismiss function, but not pass in a Binding (you can't anyway).
  • If I present DetailView directly, I will pass in the Binding as before, but not assign the closure.

Then, when I press the button inside DetailView, I will attempt to

  1. Set the Binding to false
  2. Call the closure

The order doesn't matter, because one of them will always be nil.

DetailView:

struct DetailView: View {
    var isPresented: Binding<Bool>? /// Optional `Binding` from before

    var donePressed: (() -> Void)? /// The optional closure I just added

    var body: some View {
        Button("Done") {

            /// Attempt to set the `Binding` (dismiss the `.sheet` if SwiftUI)
            isPresented?.wrappedValue = false

            /// Attempt to call the closure (call the `self.dismiss` if UIKit)
            donePressed?()

        }
    }
}

DetailView_UIKit:

override func loadView() {
    
    view = UIView()
    
    /// Host the `DetailView`
    let detailViewController = UIHostingController(
    rootView: DetailView() /// I DO NOT pass in a `Binding` here!
    )
    
    /// Assign the closure!
    detailViewController.donePressed = { [weak self] in
        self?.dismissThisViewController()
    }
    
    self.addChild(detailViewController)
    view.addSubview(detailViewController.view)
    detailViewController.view.frame = view.bounds
    detailViewController.view.autoresizingMask = [.flexibleWidth, .flexibleHeight]
    detailViewController.didMove(toParent: self)
}

/// Call this function in the closure
func dismissThisViewController() {
    self.dismiss(animated: true, completion: nil)
}

Upvotes: 14

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