How to customize the SwiftUI ViewBuilder - arrays

Question

There are some posts about SwiftUI Builder like this. So that I can embed my content like:
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)
}
}
}
I'm wondering if I don't pass the ViewBuilder in init. Instead I'd like to do something like:
struct ContentView: View {
var body: some View {
Container().buildContent {
Text("Content 1").tag(0)
Text("Content 2").tag(1)
}
}
}
The reason why I want to do this is because I want to mimic the TabView's tabItem.

Answer 1

You can't have the buildContent function mutate the Container, but you can default to having a Container that just vends an EmptyView, and the use that as a springboard for creating a new Container with your desired content.
You could achieve that sort of API like this:
struct Container<Content>: View where Content: View {
var content: Content
init(#ViewBuilder content: () -> 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: () -> 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)
}
}
}