Paging size and item size are customizable by changing values
Swift 5 supported
let collectionViewMargin = CGFloat(40)
let itemSpacing = CGFloat(15)
let itemHeight = CGFloat(300)
var itemWidth = CGFloat(0)
func horizontalPagingSetting() {
let customLayout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
itemWidth = UIScreen.main.bounds.width - collectionViewMargin * 2.0
customLayout.sectionInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
customLayout.itemSize = CGSize(width: itemWidth, height: itemHeight)
customLayout.headerReferenceSize = CGSize(width: collectionViewMargin, height: 0)
customLayout.footerReferenceSize = CGSize(width: collectionViewMargin, height: 0)
customLayout.minimumLineSpacing = itemSpacing
customLayout.scrollDirection = .horizontal
customCollectionView.collectionViewLayout = customLayout
customCollectionView.decelerationRate = UIScrollView.DecelerationRate.fast
}
func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
let pageWidth = Float(itemWidth + itemSpacing)
let contentWidth = Float(customCollectionView!.contentSize.width)
let targetXContentOffset = Float(targetContentOffset.pointee.x)
var newPage = Float(self.pageControl.currentPage)
if velocity.x == 0 {
newPage = floor((targetXContentOffset - Float(pageWidth) / 2) / Float(pageWidth)) + 1.0
}
else {
newPage = Float(velocity.x > 0 ? self.pageControl.currentPage + 1 : self.pageControl.currentPage - 1)
if newPage < 0 {
newPage = 0
}
if (newPage > contentWidth / pageWidth) {
newPage = ceil(contentWidth / pageWidth) - 1.0
}
}
self.pageControl.currentPage = Int(newPage)
let point = CGPoint (x: CGFloat(newPage * pageWidth), y: targetContentOffset.pointee.y)
targetContentOffset.pointee = point
}