Why is Page Control not reflecting where I am on the UIScrollView?

Question

After editing my UIScrollView size, page control stopped working. You can see there are only 3 slides. But (1) Page Control isn't reflecting which slide I'm on and (2) I can only scroll from slide 1 to slide 3. Here's my code: func setupSlideScrollView(slides : [Slide]) { scrollView.frame = CGRect(x: 0, y: 0, width: view.frame.width, height: 154) scrollView.contentSize = CGSize(width: 188 * CGFloat(slides.count) + CGFloat((slides.count - 1) * 10), height: 153) scrollView.isPagingEnabled = true var lastCellMaxX: CGFloat = 0 let constantSpacingBetweenCell: CGFloat = 10 for i in 0 ..< slides.count { slides[i].frame = CGRect(x: lastCellMaxX, y: 0, width: 220, height: 153) scrollView.addSubview(slides[i]) lastCellMaxX += 188 + constantSpacingBetweenCell } } func scrollViewDidScroll(_ scrollView: UIScrollView) { let pageIndex = round(scrollView.contentOffset.x/scrollView.frame.size.width) pageControl.currentPage = Int(pageIndex) } JavaScript questions and answers, JavaScript questions pdf, JavaScript question bank, JavaScript questions and answers pdf, mcq on JavaScript pdf, JavaScript questions and solutions, JavaScript mcq Test , Interview JavaScript questions, JavaScript Questions for Interview, JavaScript MCQ (Multiple Choice Questions)

Answer 1

func scrollViewDidScroll(_ scrollView: UIScrollView) { // This will always round down to zero // since the contentOffset.x will always be smaller than the frame width... let pageIndex = round(scrollView.contentOffset.x/scrollView.frame.size.width) // Possible logic to correct this? let pageIndex = scrollView.contentOffset.x / (width of a slide) pageControl.currentPage = Int(pageIndex) } -- Updated due to chat -- Your scrollview's frame is fine. However, you need to add a stackview to hold all your slides in order to scroll through it. Scrollviews are a bit tricky since you can't just add views and expect it to be scrollable. Here is test code I used to create a scrollView that contains stackviews. func createSlideshow() { scrollView.translatesAutoresizingMaskIntoConstraints = false let slide1 = UIView(frame: CGRect(x: 0, y: 0, width: 220, height: 375)) slide1.backgroundColor = UIColor.red let slide2 = UIView(frame: CGRect(x: 0, y: 0, width: 220, height: 375)) slide2.backgroundColor = UIColor.blue let slide3 = UIView(frame: CGRect(x: 0, y: 0, width: 220, height: 375)) slide3.backgroundColor = UIColor.yellow let slides: [UIView] = [slide1, slide2, slide3] let stackView = UIStackView() stackView.translatesAutoresizingMaskIntoConstraints = false stackView.axis = .horizontal stackView.alignment = .center stackView.distribution = .equalCentering stackView.spacing = 10 for slide in slides { stackView.addArrangedSubview(slide) slide.widthAnchor.constraint(equalToConstant: slide.frame.width).isActive = true slide.heightAnchor.constraint(equalTo: stackView.heightAnchor).isActive = true } scrollView.addSubview(stackView) stackView.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor).isActive = true stackView.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor).isActive = true stackView.topAnchor.constraint(equalTo: scrollView.topAnchor).isActive = true stackView.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor).isActive = true stackView.widthAnchor.constraint(greaterThanOrEqualTo: scrollView.widthAnchor).isActive = true stackView.heightAnchor.constraint(equalTo: scrollView.heightAnchor).isActive = true }