scrolling between invisible rects - ios

Question

Take a look at this picture :
Imagine a scroll view, where the pink rects are images each on a scroller page.
Imagine that the blue rects are invisible rects different in size on each page.
Imagine that the yellow rect is an image that is static = not on the scroll view.
I would like to scroll between 2 and 3, where the yellow stay at the same position, BUT it disappear when the blue rects moving. (you see it only inside)
In rect 3 you can see what happen to the yellow while scrolling .
How should I put my layers on the scroller to create such an effect ?

Answer 1

So based on comments, it look like you need a scrollview with simple views.
This views can be with overlay that has a hole inside, take a look at code for making layer with hole:
func layerWith(img: UIImage) -> CALayer {
let overlay = UIView(frame: CGRect(x: 0, y: 0,
width: UIScreen.main.bounds.width,
height: UIScreen.main.bounds.height))
// Create the initial layer from the view bounds.
let maskLayer = CAShapeLayer()
maskLayer.frame = overlay.bounds
let myImage = UIImage(named: "star")?.cgImage
maskLayer.frame = myView.bounds
maskLayer.contents = myImage
// Create the frame.
let radius: CGFloat = 150.0
let rect = CGRect(x: overlay.frame.midX - radius,
y: overlay.frame.midY - radius,
width: 2 * radius,
height: 2 * radius)
// Create the path.
let path = UIBezierPath(rect: overlay.bounds)
maskLayer.fillRule = kCAFillRuleEvenOdd
// Append the rect to the path so that it is subtracted.
path.append(UIBezierPath(rect: rect))
maskLayer.path = path.cgPath
// Set the mask of the view.
overlay.layer.mask = maskLayer
// Add the view so it is visible.
return overlay
}
And some code to add subviews into scrollview:
var i: CGFloat = 0
//or width that you want
let width = UIApplication.shared.keyWindow!.frame.width
for item in items {
let frame = CGRect(x: width * i, y: 0, width: width, height: scrollView.frame.height)
let v = UIView(frame: frame)
//here you can add layer from code above to this view before adding it to scrollview
v.layer.addSublayer(layerWith(img:your image goes here))
self.scrollView.addSubview(v)
i += 1
}