LibraryContentProvider in Xcode

LibraryContentProvider protocol in Xcode is a way for adding custom views and view modifiers to the Xcode library, which enables drag and dropping them to the SwiftUI preview. Xcode automatically looks for types implementing the protocol and then adds items to the library. It takes so little code that it makes sense to do it if you are using the library for building views.

As an example, we’ll add a custom SwiftUI view SubtitledButton to the library.

	struct SubtitledButton: View {
	let title: LocalizedStringKey
	let subtitle: LocalizedStringKey
	let action: () -> Void
	var body: some View {
	Button(action: action, label: {
	VStack(spacing: 4) {
	Text(title)
	Text(subtitle)
	.font(.footnote)
	}
	})
	}
	}

view raw SubtitledButton.swift hosted with ❤ by GitHub

The only thing we need to do is creating a new type which conforms to LibraryContentProvider and then returning the button as a LibraryItem.

	struct LibraryContent: LibraryContentProvider {
	var views: [LibraryItem] {
	return [
	LibraryItem(SubtitledButton(title: "Title",
	subtitle: "Subtitle",
	action: {}),
	title: "SubtitledButton",
	category: .control)
	]
	}
	}