Display a CGImage that you made on the fly in a SwiftUI View

MyView.swift

struct MyView: View {

    @State var cgImage: CGImage? = nil

    var imageView: Image {
        if let image = cgImage {
            Image(decorative: image, scale: 1.0, orientation: .up)
        } else {
            Image(size: CGSize(width: 640.0, height: 480.0)) { (gc: inout GraphicsContext) in
                let p = Path(CGRect(x: 0, y: 0, width: 640, height: 480))
                gc.fill(p, with: .color(.red))
                gc.draw(Text("Hello, World"), in: CGRect(x: 0, y: 0, width: 640, height: 480))
            }
        }
    }

    var body: some View {
    
      // la la la
      self.imageView
          .resizable()
          .aspectRatio(contentMode: .fit)

    }
}