將綁定傳遞給 SwiftUI 視圖的 UIKit UIViewController

Question

我正在嘗試在 UIKit 中提供 SwiftUI View 。 目前，有一個Binding<Bool>用於關閉/呈現DetailView 。 這是工作代碼：

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
    }
}

當您按下“完成”按鈕時，它isPresented設置為 false，從而關閉工作表。 現在我想從UIViewController呈現DetailView 。 這是我到目前為止：

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)
    }
}

這有效，但“完成”按鈕沒有做任何事情...... Binding仍然為零，因為我沒有將它分配給任何東西。 如何在DetailView_UIKit創建某種@State屬性，以便我可以將其傳遞給DetailView ？ 當該屬性設置為false時，我希望調用dismissThisViewController 。 或者也許創建@State屬性不是正確的方法，我不確定。

SwiftUI 流程：

ContentView (present)→ DetailView
        ◟________________◞
             Binding

UIKit 流程：

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

謝謝你的幫助！

Answer 1

所以事實證明你不能在UIViewController和View之間使用Binding 。

最后，我只是在DetailView做了一個可選的閉包。

• 如果我提供DetailView_UIKit ，我會將閉包分配給一個解除函數，但不傳入Binding （無論如何你不能）。
• 如果我直接呈現DetailView ，我會像以前一樣傳入Binding ，但不會分配閉包。

然后，當我按下DetailView的按鈕時，我會嘗試

1. 將Binding設置為 false
2. 調用閉包

順序無關緊要，因為其中之一將始終為零。

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)
}