2

我正在尝试做最简单的事情。我只想以编程方式调用一个新的 SwiftUI 视图——不是使用按钮，而是使用代码。我已经阅读了几十篇关于此的帖子和 Apple 文档 - 但我发现的几乎所有内容都与已重命名或弃用的代码有关。我发现的最接近的是：

NavigationLink(destination: NewView(), isActive: $something) {
    EmptyView()
}

但这在 Xcode Beta 7 中对我不起作用。这是一个简单的应用程序：

struct ContentView: View {
    @State private var show = false

    var body: some View {

        VStack {
            Text("This is the ContentView")

            Toggle(isOn: $show) {
                Text("Toggle var show")
            }
            .padding()

            Button(action: {
                self.show = !self.show
            }, label: {
                Text(self.show ? "Off" : "On")
            })
            Text(String(show))

            //this does not work - the ContentView is still shown
            NavigationLink(destination: SecondView(), isActive: $show)
            {
             EmptyView()
            }

            //this does not work - it adds SecondView to ContentView
            //I want a new view here, not an addition
            //to the ContentView()
//            if show {
//                //I want a new view here, not an addition to the ContentView()
//                SecondView()
//            }
        }
    }

}

以及极其简单的目的地：

struct SecondView: View {
    var body: some View {
        Text("this is the second view!")
    }
}

我一定错过了一些非常简单的东西。任何指导将不胜感激。iOS 13.1、卡特琳娜 19A546d、Xcode 11M392r

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1 回答 1

2

有几件事。首先，NavigationLink 必须嵌入到 NavigationView 中才能工作。其次，链接不需要您显示的视图。这应该显示第二个视图。我将留给您更新其他元素。

 var body: some View {
    NavigationView{
        VStack {
            Text("This is the ContentView")

            Toggle(isOn: $show) {
                Text("Toggle var show")
            }
            .padding()

            Button(action: {
                self.show = !self.show
            }, label: {
                Text(self.show ? "Off" : "On")
            })
            Text(String(show))

            //this does not work - the ContentView is still shown
            NavigationLink(destination: SecondView()){
            Text("Click to View")}
            Spacer()
//                {
//                    EmptyView()
//                }

            //this does not work - it adds SecondView to ContentView
            //I want a new view here, not an addition
            //to the ContentView()
            //            if show {
            //                //I want a new view here, not an addition to the ContentView()
            //                SecondView()
            //            }
        }
    }
}
于 2019-09-03T00:35:30.950 回答