Issue #855

Use CoreImage to generate QR image

import SwiftUI
import CoreImage.CIFilterBuiltins

struct QRView: View {
    let qrCode: String
    @State private var image: UIImage?

    var body: some View {
        ZStack {
            if let image = image {
                Image(uiImage: image)
                    .resizable()
                    .interpolation(.none)
                    .frame(width: 210, height: 210)
            }
        }
        .onAppear {
            generateImage()
        }
    }

    private func generateImage() {
        guard image == nil else { return }

        let context = CIContext()
        let filter = CIFilter.qrCodeGenerator()
        filter.message = Data(qrCode.utf8)

        guard
            let outputImage = filter.outputImage,
            let cgImage = context.createCGImage(outputImage, from: outputImage.extent)
        else { return }

        self.image = UIImage(cgImage: cgimg)
    }
}