QR Sample Code error

In the code examples where the VNImageRequestHandler results are passed to ARFrame.hitTest, the coordinates are flipped horizontally (when in portrait mode) because the coordinate system for screen coordinates mirrors Vision Framework coordinates. This can be fixed by setting up the handler with the line
let handler = VNImageRequestHandler(cvPixelBuffer: currentFrame.capturedImage, orientation: .downMirrored)

@stephen_miller Please check out the updated version of the book when you get a chance:

https://store.raywenderlich.com/products/apple-augmented-reality-by-tutorials

I hope it helps!