如何让我的 SwiftUI UIViewRepresentable 在预览中尊重内部内容大小？

Question

When I create a view in SwiftUI and render it in an Xcode preview, using PreviewLayout.sizeThatFits , the preview adjusts its size according to its content. When I import a UIKIt view using UIViewRepresentable , it appears with a full device-size frame.

Is there a way to make SwiftUI respect the intrinsicContentSize of UIView subclasses?

struct Label: UIViewRepresentable {

    func makeUIView(context: UIViewRepresentableContext<Label>) -> UILabel {
        return UILabel()
    }

    func updateUIView(_ uiView: UILabel, context: UIViewRepresentableContext<Label>) {
        uiView.text = "Some text"
    }
}

#if DEBUG
struct Label_Previews: PreviewProvider {
    static var previews: some View {
        Group {
            Label().previewLayout(.sizeThatFits)
        }
    }
}
#endif

Answer 1

Add the following to your updateUIView function:

uiView.setContentHuggingPriority(.defaultHigh, for: .vertical)
uiView.setContentHuggingPriority(.defaultHigh, for: .horizontal)

Answer 2

You can also limit the UIViewRepresentable size from the SwiftUI side .

For this you can use fixedSize :

struct Label_Previews: PreviewProvider {
    static var previews: some View {
        Label()
            .fixedSize()
            .previewLayout(.sizeThatFits)
    }
}

You can also fix the view size in one dimension only:

.fixedSize(horizontal: false, vertical: true)