Swift :- How to add offset to UIImageview inside UIScrollview in Swift? - ios

Question

In my iOS app, I have a scroll view which has the image view to scroll and zoom images.
What I am unable to do is launch the image view with pre-defined offset and zoom value.
Right now, on launch, the original image is shown which I can zoom-in/out and scroll, but I wanted to zoom-in/out with an offset with default values.
On setting the scrollview.zoomScale, I am not able to scroll the image completely.
Code below:-
let scroller = UIScrollView()
scroller.translatesAutoresizingMaskIntoConstraints = false
scroller.minimumZoomScale = 1
scroller.maximumZoomScale = 5
return scroller
}()
let imageView: UIImageView = {
let iv = UIImageView()
iv.contentMode = .scaleAspectFit
iv.translatesAutoresizingMaskIntoConstraints = false
return iv
}()

Answer 1

The first step:
scrollView = UIScrollView(frame: view.bounds)
view.addSubview(scrollView)
imageView.center = view.center
scrollView.addSubview(imageView)
scrollView.minimumZoomScale = 1.0
scrollView.maximumZoomScale = 2.0
scrollView.delegate = self
Step 2: implement the UIScrollViewDelegate method
func viewForZooming(in scrollView: UIScrollView) -> UIView? {
return imageView
}
Finally:
private func setImagePosition(_ image: UIImage) {
imageView.image = image
let size = imageSize(WithScreen: image)
imageView.frame = CGRect(x: 0, y: 0, width: size.width, height: size.height)
scrollView?.contentSize = size
if let scrollView = scrollView, size.height < scrollView.bounds.size.height {
let offsetY = (scrollView.bounds.size.height - size.height) * 0.5
scrollView.contentInset = UIEdgeInsets(top: offsetY, left: 0, bottom: offsetY, right: 0)
}
}
private func imageSize(WithScreen image: UIImage) -> CGSize {
var size = UIScreen.main.bounds.size
size.height = image.size.height * size.width / image.size.width
return size
}