Image Zoom not working in a UIScrollView inside a Root UIScrollView - ios

Question

I'm trying to zoom an image that is inside a UIScrollView, and that UIScrollView it's inside of a root UIScrollView that allow paging, similar to the Photos app.
In the viewDidLoad() inside the view that contains the root scrollView I call prepareScrollView()
func prepareScrollView(){
let tap = UITapGestureRecognizer(target: self, action: #selector(hideNavigationItem))
scrollView.addGestureRecognizer(tap)
scrollView.delegate = self
scrollView.minimumZoomScale = 1.0
scrollView.maximumZoomScale = 4.0
scrollView.zoomScale = 1.0
let width = self.view.bounds.width
let height = self.view.bounds.height
totalWidth = width * CGFloat((imageArray!.count)!) //The width must be the width of the screen by the number of the images in the array
scrollView.contentSize = CGSize(width: totalWidth, height: height)
scrollView.isPagingEnabled = true
loadPages()
}
The loadPages() function load every scrollView with their image and add it to the root scrollview.
func loadPages(){
for i in 0...((imageArray!.count)! - 1){
let pageScroll = Page(frame: CGRect(x: self.view.bounds.size.width * CGFloat(i), y: self.view.frame.origin.y, width: self.view.bounds.size.width, height: self.view.bounds.size.height))
pageScroll.minimumZoomScale = 1.0
pageScroll.maximumZoomScale = 4.0
pageScroll.zoomScale = 1.0
let imageView = UIImageView(frame: CGRect(x: 0, y: 0, width: self.view.bounds.size.width, height: self.view.bounds.size.height))
imageView.image = UIImage(data: (imageArray![i])!)
imageView.contentMode = .scaleToFill
pageScroll.addSubview(imageView)
scrollView.addSubview(pageScroll)
}
}
The Page object it's just a UIScrollView object.
class Page: UIScrollView {
func viewForZooming(in scrollView: UIScrollView) -> UIView? {
return self.subviews[0]//Return the image
}
}
And inside the root scrollView viewForZooming function it calls the viewForZooming function of the correspond child scrollview.
func viewForZooming(in scrollView: UIScrollView) -> UIView? {
if(self.scrollView.subviews.count > 0){
let childScrollView = self.scrollView.subviews[currentPage] as! Page
let image = childScrollView.viewForZooming(in: scrollView)
return image
}
return nil
}
With this approach I can navigate horizontally but I can't zoom in the current image. The viewForZooming function executes in both objects. What I'm doing wrong?

Answer 1

Finally I solve my issue. I changed the Page object to a simple UIScrollView and then set the delegate of the scrollView object to self.
func loadPages(){
for i in 0...((comic?.comicsPages!.count)! - 1){
let pageScroll = UIScrollView(frame: CGRect(x: self.view.bounds.size.width * CGFloat(i), y: self.view.frame.origin.y, width: self.view.bounds.size.width, height: self.view.bounds.size.height))
pageScroll.minimumZoomScale = 1.0
pageScroll.maximumZoomScale = 4.0
pageScroll.zoomScale = 1.0
pageScroll.isUserInteractionEnabled = true
pageScroll.delegate = self //Here
let imageView = UIImageView(frame: CGRect(x: 0, y: 0, width: self.view.bounds.size.width, height: self.view.bounds.size.height))
imageView.image = UIImage(data: (imageArray![i])!)
imageView.contentMode = .scaleToFill
pageScroll.addSubview(imageView)
scrollView.addSubview(pageScroll)
}
}
And then in the viewForZooming function of the root scrollView I change the code for this:
func viewForZooming(in scrollView: UIScrollView) -> UIView? {
if(scrollView.subviews.count > 0){
return scrollView.subviews[0]
}
return nil
}
The scrollView parameter is the child scrollview so it works as expected.