SwiftUI中调用OID认证方法时如何将View转为UIViewController？

SwiftUI的View是结构体类型，和UIKit的UIViewController分属不同框架体系，直接传入MainView实例必然会出现类型不匹配错误。你需要获取当前SwiftUI视图所在的UIKit容器控制器，以下是两种可行方案：

方案一：通过UIApplication获取顶层ViewController #

给UIApplication编写扩展，用来获取当前应用的顶层可见ViewController：

extension UIApplication {
    func topViewController(controller: UIViewController? = UIApplication.shared.keyWindow?.rootViewController) -> UIViewController? {
        if let navigationController = controller as? UINavigationController {
            return topViewController(controller: navigationController.visibleViewController)
        }
        if let tabController = controller as? UITabBarController {
            if let selected = tabController.selectedViewController {
                return topViewController(controller: selected)
            }
        }
        if let presented = controller?.presentedViewController {
            return topViewController(controller: presented)
        }
        return controller
    }
}

在MainView中调用该方法获取顶层VC，替换原代码中错误的vc实例：

struct MainView: View {
    var body: some View {
        // 示例：在按钮点击事件中触发认证
        Button("发起认证") {
            guard let topVC = UIApplication.shared.topViewController() else {
                print("无法获取顶层ViewController")
                return
            }
            
            // 确保request已正确初始化
            appDelegate.currentAuthorizationFlow = OIDAuthState.authState(byPresenting: request, presenting: topVC) { authState, error in
                if let authState = authState {
                    print("获取到授权令牌. Access token: \(authState.lastTokenResponse?.accessToken ?? "nil")")
                } else {
                    print("授权错误: \(error?.localizedDescription ?? "未知错误")")
                }
            }
        }
    }
}

方案二：自定义UIHostingController并传递引用 #

如果需要更精准控制当前视图的容器控制器，可以在App入口处自定义UIHostingController，并将其引用传递给SwiftUI视图：

1. 在App入口（@main结构体）中保存UIHostingController引用：

@main
struct YourApp: App {
    @State private var hostingVC: UIViewController?
    
    var body: some Scene {
        WindowGroup {
            MainView(hostingVC: $hostingVC)
                .onAppear {
                    hostingVC = UIApplication.shared.topViewController()
                }
        }
    }
}

2. 在MainView中接收引用并使用：

struct MainView: View {
    @Binding var hostingVC: UIViewController?
    
    var body: some View {
        Button("发起认证") {
            guard let vc = hostingVC else { return }
            
            appDelegate.currentAuthorizationFlow = OIDAuthState.authState(byPresenting: request, presenting: vc) { authState, error in
                if let authState = authState {
                    print("获取到授权令牌. Access token: \(authState.lastTokenResponse?.accessToken ?? "nil")")
                } else {
                    print("授权错误: \(error?.localizedDescription ?? "未知错误")")
                }
            }
        }
    }
}

关键修正点 #

你原代码中的let vc = MainView()是错误写法，MainView是SwiftUI视图结构体，并非UIViewController实例，必须替换为上述方案中获取的UIKit控制器实例。

内容的提问来源于stack exchange，提问作者Alexander Paul