Ios Swiftui为什么在点击第二行之前背景不起作用

我有一个共享视图控制器连接到一个列表.当用户点击列表行时，共享视图应该弹出并显示点击列表的内容.问题是，当我启动应用程序并点击列表项时，共享视图文本为空，如果我点击第二个不同的项目，它会显示内容:

//示例:启动应用程序，单击列表1并查看没有显示任何内容，然后单击列表2并显示内容.

我怎样才能使你第一次点击列表时，内容显示在ShareView控制器中.这是一个小项目

import SwiftUI

struct ContentView: View {
    let StringList = ["List 1","List 2","List 3","List 4","List 5"]
    @State var TextExample = ""
    @State var IsOpen = false
    var body: some View {
        List {
            ForEach(StringList, id: \.self) { string in
                Text(string)
                    .onTapGesture {
                        TextExample = string
                        IsOpen = true
                    }
            }
        }.background(SharingViewController(isPresenting: $IsOpen) {
            print("\(TextExample)")
            let av = UIActivityViewController(activityItems: [TextExample], applicationActivities: nil)
            av.completionWithItemsHandler = { _, _, _, _ in
                IsOpen = false // required for re-open !!!
               }
               
            return av
        })
    }
}

struct SharingViewController: UIViewControllerRepresentable {
    @Binding var isPresenting: Bool

    var content: () -> UIViewController

    func makeUIViewController(context: Context) -> UIViewController {
        UIViewController()
    }

    func updateUIViewController(_ uiViewController: UIViewController, context: Context) {

        if isPresenting  {
            uiViewController.present(content(), animated: true, completion: nil)

        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

任何建议都很好