GeometryReader与ScrollView的结合

Question

我试图使用GeometryReader将maxHeight分配给Scrollview中的列表。

为了解决这个问题，我创建了以下项目：GeometryReaderTesting。

它使用以下参数设置ContentView：

• 文本。
• 列表。
• 文本。 我使用@ViewBuilder将列表和最后文本提取到自己的视图中，并希望将列表的maxHeight设置为用户屏幕高度的.5。

问题是，应用程序不会生成以下错误，而且GeometryReader似乎没有计算出正确的高度：

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这是我的ContentView代码，如果有人知道我做错了什么…

struct ContentView: View {

    let arrayWithStuff = [ "one","two","three","four","five","six","seven","eight","nine","ten", "eleven", "twelve"]

    var heightOfView: CGFloat = 0.0 // To be set by GeometryReader

    var body: some View {

    let myString = "Top of Test App"

     return   ZStack {
            GeometryReader { g in
                heightOfView = g.size.height
        NavigationView {

            print("height of view : \(heightOfView)")
             ScrollView {
                VStack {
                    Text(myString)
                    .padding()
                    Divider()
                    self.ViewBody()
                } // END of Vstack
                    .navigationBarTitle("Test App", displayMode: .inline)
            } // END of Scrollview
                }//End of NavigationView
            } // End of Geometry reader
        } // End of Zstack

  } // End of body


    @ViewBuilder func ViewBody() -> some View {
        VStack {
            List {
                ForEach (self.arrayWithStuff, id: \.self) { item in
                    Text(item) }
            } // END of List
                .frame(maxHeight: heightOfView*0.5)
            Divider()
            Text("Bottom of TEST APP")
        }
        .padding()
    }
}

再一次，任何帮助都将不胜感激。

Answer 1

下面是一个可能的解决方案的演示。用Xcode 11.4测试。

​

​

struct ContentView: View {

    let arrayWithStuff = [ "one","two","three","four","five","six","seven","eight","nine","ten", "eleven", "twelve"]

    var body: some View {

        let myString = "Top of Test App"

        return   ZStack {
            GeometryReader { g in
                NavigationView {
                    ScrollView {
                        VStack {
                            Text(myString)
                                .padding()
                            Divider()
                            self.ViewBody(height: g.size.height)
                        } // END of Vstack
                            .navigationBarTitle("Test App", displayMode: .inline)
                    } // END of Scrollview
                }//End of NavigationView
            } // End of Geometry reader
        } // End of Zstack

    } // End of body


    func ViewBody(height: CGFloat) -> some View {
        print("height of view : \(height)")
        return VStack {
            List {
                ForEach (self.arrayWithStuff, id: \.self) { item in
                    Text(item) }
            } // END of List
                .frame(height: height*0.5)
            Divider()
            Text("Bottom of TEST APP")
        }
        .padding()
    }
}