Make your cells perfectly scroll to content

CollectionSnapFlowLayout.swift

class CollectionSnapFlowLayout: UICollectionViewFlowLayout {
	
	var onlyScrollToNext: Bool = true
	
	override func targetContentOffset(forProposedContentOffset proposedContentOffset: CGPoint, withScrollingVelocity velocity: CGPoint) -> CGPoint {
		guard let collectionView = self.collectionView else {
			let latestOffset = super.targetContentOffset(forProposedContentOffset: proposedContentOffset, withScrollingVelocity: velocity)
			return latestOffset
		} /// Add some snapping behaviour so that the cell is always centered
		var proposedX: CGFloat = proposedContentOffset.x
		if velocity.x >= 0, onlyScrollToNext {
			proposedX = min(proposedContentOffset.x, collectionView.contentOffset.x + (itemSize.width) / 2)
		} else if velocity.x < 0, onlyScrollToNext {
			proposedX = max(proposedContentOffset.x, collectionView.contentOffset.x - (itemSize.width) / 2)
		}

		let targetRect = CGRect(x: proposedX, y: proposedContentOffset.y, width: collectionView.frame.width, height: collectionView.frame.height)
		guard let rectAttributes = super.layoutAttributesForElements(in: targetRect) else { return .zero }
		let horizontalCenter = proposedX + collectionView.frame.width / 2
		var offsetAdjustment: CGFloat = .greatestFiniteMagnitude
		
		for layoutAttributes in rectAttributes {
			let itemHorizontalCenter = layoutAttributes.center.x
			if (itemHorizontalCenter - horizontalCenter).magnitude < offsetAdjustment.magnitude {
				offsetAdjustment = itemHorizontalCenter - horizontalCenter
			}
		}
		return CGPoint(x: proposedX + offsetAdjustment, y: proposedContentOffset.y)
	}
}