A SwiftUI wrapper around NSBox

box.swift

/// A SwiftUI wrapper around `NSBox`. 
public struct Box<Content>: View where Content: View {
    private let title: String?
    private let content: () -> Content

    public init(_ title: String? = nil, @ViewBuilder content: @escaping () -> Content) {
        self.title = title
        self.content = content
    }

    public var body: some View {
        VStack(alignment: .leading) {
            if let title = title {
                SwiftUI.Text(title)
            }
            BoxContent(content: content)
        }
    }
}

private struct BoxContent<Content>: NSViewRepresentable where Content: View {
    private let content: () -> Content

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

    func updateNSView(_ box: NSBox, context: Context) {
    }

    func makeNSView(context: Context) -> NSBox {
        let box = NSBox()
        box.titlePosition = .noTitle
        box.contentViewMargins = NSSize(width: 1, height: 2)

        let contentView = NSHostingView(rootView: content())
        contentView.wantsLayer = true
        contentView.layer?.cornerRadius = 4
        contentView.layer?.masksToBounds = true
        box.contentView = contentView
        return box
    }
}