SwiftUIビューのUIViewControllerにアクセスする

適当なUIViewControllerRepresentableビューコントローラーを作り追加して他のビューコントローラーへアクセスするコードです。多少強引で黒魔術っぽい方法だろうけど、どうしてもそうしたい時に。

import SwiftUI

public struct ControllerRepresenterView: UIViewControllerRepresentable {
    public typealias UIViewControllerType = UIViewController
    
    private final class ViewController: UIViewController {
        var willAppear: (UIViewController) -> Void = { _ in }
        var didAppear: (UIViewController) -> Void = { _ in }
        override func viewWillAppear(_ animated: Bool) {
            super.viewWillAppear(animated)
            willAppear(self)
        }
        override func viewDidAppear(_ animated: Bool) {
            super.viewDidAppear(animated)
            didAppear(self)
        }
    }
    
    private let viewController = ViewController()
    
    public init(
        willAppear: @escaping (UIViewController) -> Void,
        didAppear: @escaping (UIViewController) -> Void
    ) {
        viewController.willAppear = willAppear
        viewController.didAppear = didAppear
    }
    
    public func makeUIViewController(context: Context) -> UIViewControllerType {
        viewController
    }
    
    public func updateUIViewController(_ uiViewController: UIViewControllerType, context: Context) {
        //
    }
}

使用例

import SafariServices

struct ContentView: View {
    func doNothing(uiViewController: UIViewController) {}
    
    func example(uiViewController: UIViewController) {
        // contentへアクセスする為に
        guard let viewController = uiViewController.parent else { return }
        // ex1: 黄色から青色へ
        viewController.view.subviews.last?.backgroundColor = UIColor.systemBlue
        // ex2: 1秒後にフルスクリーンモーダル表示
        DispatchQueue.main.asyncAfter(deadline: .now() + 1.0) {
            let a = "https://www.apple.com/"
            guard let u = URL(string: a) else { return }
            let c = SFSafariViewController(url: u)
            c.modalPresentationStyle = .overFullScreen
            viewController.present(c, animated: true, completion: nil)
        }
    }
    
    var content: some View {
        Color.yellow
    }
    
    var body: some View {
        Group {
            content
        }
        .background(
            ControllerRepresenterView(willAppear: doNothing, didAppear: example)
        )
    }
}