Collectionview the end Draging Position dont stop on each cell - swift

Question

could somebody help me?
I have Collection view with insets, Scroll Direction Horizontal, Paging enables and no space between cells. And the issue is that the paging doesn't stop on each cell.
I tried all possible solution which I can find on StackOverflow and the World Wide Web but nothing works. I use Xcode 10 and Swift5 and this is for an iPhone app. I don't add my collectionviewcell code because it have only the IBoutlet for the Label.
class ViewController: UIViewController, UICollectionViewDataSource,
UICollectionViewDelegate {
#IBOutlet weak var collectionView: UICollectionView!
private let item = ["Monday","Tuesday","Wednesday","Thursday","Friday","Saturday", "Sunday"]
private let cellScaling: CGFloat = 0.33
private var cellWidth: CGFloat = 0
override func viewDidLoad() {
super.viewDidLoad()
UpdateUI()
}
func UpdateUI(){
self.collectionView.backgroundColor = UIColor.white
let screenSize = UIScreen.main.bounds.size
let cellWidth = floor(screenSize.width * cellScaling)
let insetX = (view.bounds.width - cellWidth) / 2
let layout = collectionView!.collectionViewLayout as! UICollectionViewFlowLayout
layout.itemSize = CGSize(width: cellWidth, height: collectionView.bounds.height)
collectionView.contentInset = UIEdgeInsets(top: 0, left: insetX, bottom: 0, right: insetX)
// layout.minimumLineSpacing = 0
self.cellWidth = cellWidth
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return self.item.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! CollectionViewCell
cell.label.text = self.item[indexPath.row]
cell.backgroundColor = UIColor.cyan
return cell
}
private var startingScrollingOffset = CGPoint.zero
func scrollViewWillBeginDragging(_ scrollView: UIScrollView) {
startingScrollingOffset = scrollView.contentOffset
}
func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
let page: CGFloat
let offset = scrollView.contentOffset.x + scrollView.contentInset.left
let proposedPage = offset / max(1, cellWidth)
let snapPoint: CGFloat = 0.1
let snapDelta: CGFloat = offset > startingScrollingOffset.x ? (1-snapPoint) : snapPoint
if floor(proposedPage + snapDelta) == floor(proposedPage){
page = floor(proposedPage)
} else {
page = floor(proposedPage + 1)
}
targetContentOffset.pointee = CGPoint(x: cellWidth * page, y: targetContentOffset.pointee.y)
}
}
enter image description here
And please Notice that I tried all other solution what I could find. Before you vote to delete this Question. the photo shows what it should look like on every cell.

Answer 1

I had to do a similar collection view a few months ago,
This is the code that I use:
func scrollViewWillEndDragging(_ scrollView: UIScrollView, withVelocity velocity: CGPoint, targetContentOffset: UnsafeMutablePointer<CGPoint>) {
let layout = theNameOfYourCollectionView.collectionViewLayout as! UICollectionViewFlowLayout
let cellWidthIncludingSpacing = layout.itemSize.width + layout.minimumLineSpacing // Calculate cell size
let offset = scrollView.contentOffset.x
let index = (offset + scrollView.contentInset.left) / cellWidthIncludingSpacing // Calculate the cell need to be center
if velocity.x > 0 { // Scroll to -->
targetContentOffset.pointee = CGPoint(x: ceil(index) * cellWidthIncludingSpacing - scrollView.contentInset.right, y: -scrollView.contentInset.top)
} else if velocity.x < 0 { // Scroll to <---
targetContentOffset.pointee = CGPoint(x: floor(index) * cellWidthIncludingSpacing - scrollView.contentInset.left, y: -scrollView.contentInset.top)
} else if velocity.x == 0 { // No dragging
targetContentOffset.pointee = CGPoint(x: round(index) * cellWidthIncludingSpacing - scrollView.contentInset.left, y: -scrollView.contentInset.top)
}
}
This code calculates the size of your cell, how many cells have already been shown and once the scroll is finished, adjust it to leave the cell centered.
Make sure you have the pagingEnabled of your collectionView in false if you want to use this code.
I hope I help you!