init(subviews:transform:)

Declaration

init<Base, Result>(subviews view: Base, @ViewBuilder transform: @escaping (SubviewsCollection) -> Result) where Content == GroupElementsOfContent<Base, Result>, Base : View, Result : View

Parameters

• view:

  The view to get the subviews of.

• transform:

  A closure that constructs a view from the collection of subviews.

Discussion

Use this initializer to create a group that gives you programmatic access to the group’s subviews. The following CardsView defines the group’s structure based on the set of views that you provide to it:

struct CardsView<Content: View>: View {
    var content: Content

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

    var body: some View {
        VStack {
            Group(subviews: content) { subviews in
                HStack {
                    if subviews.count >= 2 {
                        SecondaryCard { subview[1] }
                    }
                    if let first = subviews.first {
                        FeatureCard { first }
                    }
                    if subviews.count >= 3 {
                        SecondaryCard { subviews[2] }
                    }
                }
                if subviews.count > 3 {
                    subviews[3...]
                }
            }
        }
    }
}

You can use CardsView with its view builder-based initializer to arrange a collection of subviews:

CardsView {
    NavigationLink("What's New!") { WhatsNewView() }
    NavigationLink("Latest Hits") { LatestHitsView() }
    NavigationLink("Favorites") { FavoritesView() }
    NavigationLink("Playlists") { MyPlaylists() }
}

Subviews collection constructs subviews on demand, so only access the part of the collection you need to create the resulting content.

Subviews are proxies to the view they represent, which means that modifiers that you apply to the original view take effect before modifiers that you apply to the subview. SwiftUI resolves the view using the environment of its container rather than the environment of its subview proxy. Additionally, because subviews represent a single view or container, a subview might represent a view after the application of styles. As a result, applying a style to a subview might have no effect.