SwiftUIで吹き出し(UIPopoverPresentationController)

@available(iOS 15, *)
extension View {
    @ViewBuilder
    func popover<Content: View>(isPresented: Binding<Bool>,_ arrowDirection: UIPopoverArrowDirection = .any, @ViewBuilder content: @escaping () -> Content) -> some View {
        self.background {
            PopoverController(isPresented: isPresented, arrowDirection: arrowDirection, content: content())
        }
    }
}
class CustomHostingView<Content: View>: UIHostingController<Content>{
    override func viewDidLoad() {
        super.viewDidLoad()
        preferredContentSize = view.intrinsicContentSize
    }
}
@available(iOS 15, *)
struct PopoverController<Content: View>: UIViewControllerRepresentable {
    @Binding var isPresented: Bool
    var arrowDirection: UIPopoverArrowDirection = .down
    var content: Content
    @State var isShown: Bool = false
    class Coordinator: NSObject, UIPopoverPresentationControllerDelegate {
        var parent: PopoverController
        init(parent: PopoverController) {
            self.parent = parent
        }
        func adaptivePresentationStyle(for controller: UIPresentationController, traitCollection: UITraitCollection) -> UIModalPresentationStyle {
            return .none
        }
        func presentationControllerWillDismiss(_ presentationController: UIPresentationController) {
            self.parent.isPresented = false
        }
        func presentationController(_ presentationController: UIPresentationController, willPresentWithAdaptiveStyle style: UIModalPresentationStyle, transitionCoordinator: UIViewControllerTransitionCoordinator?) {
            DispatchQueue.main.async {
                self.parent.isShown = true
            }
        }
    }
    func makeCoordinator() -> Coordinator {
        Coordinator(parent: self)
    }
    func makeUIViewController(context: Context) -> some UIViewController {
        let viewController = UIViewController()
        viewController.view.backgroundColor = .clear
        return viewController
    }
    func updateUIViewController(_ uiViewController: UIViewControllerType, context: Context) {
        if self.isShown {
            if !self.isPresented {
                uiViewController.dismiss(animated: true) {
                    self.isShown = false
                }
            }
        } else {
            if self.isPresented {
                let customView = CustomHostingView(rootView: content)
                customView.view.backgroundColor = .systemBackground
                customView.modalPresentationStyle = .popover
                customView.popoverPresentationController?.permittedArrowDirections = arrowDirection
                customView.popoverPresentationController?.delegate = context.coordinator
                customView.popoverPresentationController?.sourceView = uiViewController.view
                uiViewController.present(customView, animated: true)
            }
        }
    }
}

import SwiftUI
struct ContentView: View {
    @State var isPresented: Bool = false
    var body: some View {
        VStack {
            Button("Show popover", action: {
                self.isPresented.toggle()
            }).popover(isPresented: $isPresented, content: {
                Text("Hello, World!")
                    .padding(4)
            }).buttonStyle(.borderedProminent)
        }
        .padding()
    }
}