SwiftUI relative frame

View+Relative.swift

extension View {
    func relative(width: CGFloat? = nil, height: CGFloat? = nil, alignment: Alignment = .center) -> some View {
        Color.clear
            .frame(maxWidth: width.map { _ in .infinity }, maxHeight: height.map { _ in .infinity })
            .overlay(GeometryReader { proxy in
                ZStack {
                    self.frame(
                        width: width.map { proxy.size.width * $0 },
                        height: height.map { proxy.size.height * $0 }
                    )
                }
                .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: alignment)
            })
    }
}