Screenshot in part of UIView masked to UIBezierPath / CGPath - swift

Question

I'm building a drawing application. I'm drawing using CGMutablePath.
I want the user to be able to select a part of the drawn paths and then move that part, like this:
I thought, a possible solution would be to mask a view to the drawn area and then take a screenshot in that view.
In here, you can see the area drawn in which I want to take a screenshot:
To take the screenshot, I get the last path drawn, being the area the screenshot is to be taken in:
let shapeLayer = CAShapeLayer()
shapeLayer.path = last.closedPath // returns CGPath.closeSubpath()
shapeLayer.lineWidth = 10
I then create an overlayView that's the view I'm taking the screenshot in.
let overlayView = UIView(frame: view.bounds)
overlayView.backgroundColor = .black
overlayView.alpha = 0.4
view.addSubview(overlayView)
view.bringSubview(toFront: overlayView)
I'm then masking the view to the path:
overlayView.mask(withPath: UIBezierPath(cgPath: last.closedPath!))
The .mask(withPath:) method comes from here:
extension UIView {
func mask(withPath path: UIBezierPath) {
let path = path
let maskLayer = CAShapeLayer()
maskLayer.path = path.cgPath
self.layer.mask = maskLayer
}
}
Then, I take the screenshot in overlayView:
let image: UIImage = {
UIGraphicsBeginImageContextWithOptions(overlayView.bounds.size, false, 0)
defer { UIGraphicsEndImageContext() }
drawView.drawHierarchy(in: overlayView.bounds, afterScreenUpdates: true)
return UIGraphicsGetImageFromCurrentImageContext()!
}()
UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil)
What happens, is that the overlayView has the screen's full size and also draws the screenshot in the full size.
When debugging the view hierarchy, I can also see that the overlayView is still full-size, not masked to the path.
So, instead of getting only the part drawn around as screenshot, I get an image of the whole view / screen.
Question
How do I successfully mask the view to the drawn area so I can take a screenshot in that part of the screen only?

Answer 1

I think the overlayView.frame equals self.view.frame, which is why the image is being taken full screen.
A solution to your issue may be solved as follows (although I may have understood incorrectly):
let shapeLayer = CAShapeLayer()
shapeLayer.path = last.closedPath // returns CGPath.closeSubpath()
shapeLayer.lineWidth = 10
let rect = shapeLayer.path.boundingBoxOfPath
let overlayView = UIView(frame: rect)