Xcode Beta 6中的SwiftUI模块?

以前在SwiftUI(Xcode Beta 5)中,模式的工作方式如下:

struct ContentView: View {

    @State var modalIsPresented: Bool = false

    var body: some View {

        Button(action: {

            self.modalIsPresented = true

        }) {

            Text("Show modal")

        }

        .sheet(isPresented: $modalIsPresented, content: {

            ModalView()

        })

    }

}

struct ModalView: View {

    @Environment(\.presentationMode) var presentationMode

    var body: some View {

        Button(action: {

            self.presentationMode.value.dismiss()

        }) {

            Text("Hide modal")

        }

    }

}

但现在在Xcode Beta 6中,我找不到一种方法来消除模态。现在已经没有了 value 性质 presentationMode