Double Tap Zoom to The Tap Location Swift 5 iOS 13

doubleTapZoom

@objc func handleDoubleTap(_ recognizer: UITapGestureRecognizer) {
    let scale = min(scrollView.zoomScale * 2, scrollView.maximumZoomScale)

    if scale != scrollView.zoomScale { // zoom in
        let point = recognizer.location(in: imageView)

        let scrollSize = scrollView.frame.size
        let size = CGSize(width: scrollSize.width / scrollView.maximumZoomScale,
                          height: scrollSize.height / scrollView.maximumZoomScale)
        let origin = CGPoint(x: point.x - size.width / 2,
                             y: point.y - size.height / 2)
        scrollView.zoom(to:CGRect(origin: origin, size: size), animated: true)
    } else if scrollView.zoomScale == 1 { zoom out
        scrollView.zoom(to: zoomRectForScale(scale: scrollView.maximumZoomScale, center: recognizer.location(in: imageView)), animated: true)
    }
}

func zoomRectForScale(scale: CGFloat, center: CGPoint) -> CGRect {
    var zoomRect = CGRect.zero
    zoomRect.size.height = imageView.frame.size.height / scale
    zoomRect.size.width  = imageView.frame.size.width  / scale
    let newCenter = scrollView.convert(center, from: imageView)
    zoomRect.origin.x = newCenter.x - (zoomRect.size.width / 2.0)
    zoomRect.origin.y = newCenter.y - (zoomRect.size.height / 2.0)
    return zoomRect
}

Thanks for your gist. Helped me a lot. I improved it a bit (see my fork). E.g. Scrolling out is as easy as:

scrollView.setZoomScale(scrollView.minimumZoomScale, animated: true)