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July 24, 2021 06:43
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Onboarding with scaling image.
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| typealias Interval = (a: CGFloat, b: CGFloat) | |
| extension OnboardingViewController: UIScrollViewDelegate { | |
| func scrollViewDidScroll(_ scrollView: UIScrollView) { | |
| let pageIndex = round(scrollView.contentOffset.x / scrollView.frame.width) | |
| pageControl.currentPage = Int(pageIndex) | |
| let maximumHorizontalOffset: CGFloat = scrollView.contentSize.width - scrollView.frame.width | |
| let currentHorizontalOffset: CGFloat = scrollView.contentOffset.x | |
| let percentageHorizontalOffset: CGFloat = currentHorizontalOffset / maximumHorizontalOffset | |
| let percentOffset: CGPoint = CGPoint(x: percentageHorizontalOffset, y: 0.0) | |
| let intervals = makeIntervals(split: 1.0, by: pageControl.numberOfPages - 1) | |
| guard let interval = intervals.enumerated().first(where: { percentOffset.x > $0.element.a && percentOffset.x <= $0.element.b }) else { | |
| return | |
| } | |
| guard percentOffset.x > 0.0 && percentOffset.x <= 1, (interval.offset + 1) < onboardingViews.count else { | |
| return | |
| } | |
| let scaleFactor = 1.0 / CGFloat(pageControl.numberOfPages - 1) | |
| let scale0 = (interval.element.b - percentOffset.x) / scaleFactor | |
| let scale1 = percentOffset.x / interval.element.b | |
| onboardingViews[interval.offset].scaleImage(scale: scale0) | |
| onboardingViews[interval.offset + 1].scaleImage(scale: scale1) | |
| } | |
| // MARK: - Utilities | |
| private func makeIntervals(split whole: CGFloat, by n: Int) -> [Interval] { | |
| let step: CGFloat = whole / CGFloat(n) | |
| let iterations: [CGFloat] = Array.init(repeating: step, count: n) | |
| return iterations | |
| .enumerated() | |
| .map { Interval(a: $0.element * CGFloat($0.offset), b: $0.element * CGFloat($0.offset + 1)) } | |
| } | |
| } |
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Great. I am wondering where is scaleImage method?