在SwiftUI 3中，有没有人能够限制放在mac上的对象的类型？

import SwiftUI

struct ContentView: View {
    @State private var view: AnyView?

    var body: some View {
        VStack {
            Button("Show Text") {
                self.view = AnyView(Text("Hello, SwiftUI!"))
            }
            Button("Show Image") {
                self.view = AnyView(Image("example-image"))
            }
            Button("Show Custom View") {
                self.view = AnyView(CustomView())
            }
            Spacer()
            if let view = view {
                view
                    .frame(width: 200, height: 200)
                    .border(Color.gray)
            }
        }
    }
}

struct CustomView: View {
    var body: some View {
        Rectangle()
            .fill(Color.blue)
            .frame(width: 100, height: 100)
    }
}