Question

有些关于SwiftUI Builder的帖子，例如this。这样我就可以嵌入我的内容了：

declare global { interface DateAdapterType ... }

我想知道是否不通过init的ViewBuilder。相反，我想做类似的事情：

struct Container<Content>: View where Content: View {

  var content: Content

  init(@ViewBuilder content: @escaping () -> Content) {
    self.content = content()
  }

  var body: some View {
    return content
  }
}

struct ContentView: View {
  var body: some View {
    Container() {
      Text("Content 1").tag(0)
      Text("Content 2").tag(1)
    }
  }
}

我要这样做的原因是因为我想模仿 struct ContentView: View { var body: some View { Container().buildContent { Text("Content 1").tag(0) Text("Content 2").tag(1) } } } 的 TabView 。

Answer 1

您不能让buildContent函数对Container进行突变，但是您可以默认将Container仅仅出售给EmptyView，并将其用作用来创建具有所需内容的新Container的跳板。

您可以实现如下所示的API：

struct Container<Content>: View where Content: View {
    var content: Content

    init(@ViewBuilder content: @escaping () -> Content) {
        self.content = content()
    }

    var body: some View {
        return content
    }
}

extension Container where Content == EmptyView {
    init() {
        self.content = EmptyView()
    }

    /// Return a new `Container` with the given `Content` builder.
    func buildContent<V : View>(@ViewBuilder content: @escaping () -> V) -> Container<V> {
        Container<V>(content: content)
    }
}

struct ContentView: View {
    var body: some View {
        Container().buildContent {
            Text("Content 1").tag(0)
            Text("Content 2").tag(1)
        }
    }
}

如何自定义SwiftUI ViewBuilder

1 个答案: