您可以将其完全复制到操场上进行复制。当您启动它时，预览看起来不错，但是当您开始上下滚动时，项目（HStack）消失了。我不知道为什么...这是苹果的错误还是我的误解？

  //: A UIKit based Playground for presenting user interface

import UIKit
import PlaygroundSupport
import SwiftUI

struct Cell : View {

    var country: String

    var body: some View {
        VStack() {
            Text("OMG").onAppear() { print ("OMG") }
            ScrollView(.horizontal) {
                HStack() {
                    Text(country)

                }.background(Rectangle().fill(Color.blue))//.frame(height: 195)
            }.background(Rectangle().fill(Color.orange))//.frame(height: 205)

        }
    }
}

struct ContentView: View {

    var countries = ["a","b","c","d","e","f","g","h"]

    init() {
        UITableView.appearance().showsVerticalScrollIndicator = false
        UITableView.appearance().showsHorizontalScrollIndicator = false
    }

    var body: some View {

        GeometryReader() { geometry in
            VStack() {
                Text("Title")
                List(self.countries,id: \.self) { country in

                    Cell(country: country)

                }.environment(\.defaultMinListRowHeight,340)
            }
        }
    }
}

// Present the view controller in the Live View window
PlaygroundPage.current.liveView = UIHostingController(rootView: ContentView())