IconGenerationExample.swift

enum GenerationError: Error {
    case couldNotGetImageRep
    case couldNotGeneratePNG
}

extension View {

    /// Generates an image from the current View
    /// - Parameter size: The size of the image to generate
    func generateImageData(size: CGSize) throws -> Data {
        let wrapper = NSHostingView(rootView: self)
        wrapper.frame = CGRect(origin: .zero, size: size)

        let frame = CGRect(origin: .zero, size: wrapper.convertFromBacking(wrapper.bounds.size))
        guard let bitmapRepresentation = wrapper.bitmapImageRepForCachingDisplay(in: frame) else {
            throw GenerationError.couldNotGetImageRep
        }

        bitmapRepresentation.size = wrapper.bounds.size
        wrapper.cacheDisplay(in: wrapper.bounds, to: bitmapRepresentation)

        guard let data = bitmapRepresentation.representation(using: .png, properties: [:]) else {
            throw GenerationError.couldNotGeneratePNG
        }

        return data
    }
}