如何在 swiftUI 中呈現 crossDissolve 視圖？

Question

在 UIKit 中，我使用下面的代碼來呈現一個具有呈現樣式crossDissolve的模態Viewcontroller

controller.modalTransitionStyle = .crossDissolve
controller.modalPresentationStyle = .overFullScreen
UIApplication.topViewController()?.present(controller, animated: true, completion: nil)

但是我如何在 swiftUI 中實現這一點？

Answer 1

你可以像這樣在 UIViewController 上做一個擴展：

struct ViewControllerHolder {
    weak var value: UIViewController?
}

struct ViewControllerKey: EnvironmentKey {
    static var defaultValue: ViewControllerHolder {
        return ViewControllerHolder(value: UIApplication.shared.windows.first?.rootViewController)

    }
}

extension EnvironmentValues {
    var viewController: UIViewController? {
        get { return self[ViewControllerKey.self].value }
        set { self[ViewControllerKey.self].value = newValue }
    }
}

extension UIViewController {
    func present<Content: View>(style: UIModalPresentationStyle = .automatic, transitionStyle: UIModalTransitionStyle = .coverVertical, @ViewBuilder builder: () -> Content) {
        let toPresent = UIHostingController(rootView: AnyView(EmptyView()))
        toPresent.modalPresentationStyle = style
        toPresent.modalTransitionStyle = transitionStyle
        toPresent.rootView = AnyView(
            builder()
                .environment(\.viewController, toPresent)
        )
        self.present(toPresent, animated: true, completion: nil)
    }
}

並在您的 SwiftUI 代碼中隨意使用它：

struct ContentView: View {

    @Environment(\.viewController) private var viewControllerHolder: UIViewController?
    private var viewController: UIViewController? {
        self.viewControllerHolder
    }

    var body: some View {
        Button(action: {
            self.viewController?.present(style: .fullScreen, transitionStyle: .coverVertical) {
              Text("OK")
           }
        }) {
           Text("Present me!")
        }
    }
}

通過這種方式，您可以根據需要更改演示文稿和過渡樣式