Custom menu bar with collectionview - ios

Question

I want to ask. I make a custom menubar from collectionView and I want to link and change my menubar of collection view and the data from another collectionView while swiping. Here a picture what I'm try to make
but while try to swipe to left and right my menu bar is not following, I already make a reference to capture the value. but it's still not work. here is my code
class SegmentedView: UIView {
let collectionView: UICollectionView = {
let layout = UICollectionViewFlowLayout()
layout.scrollDirection = .horizontal
let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
return cv
}()
let knowledge = ["Pengetahuan", "Keterampilan", "Sikap"]
var selectedMenu: CGFloat?
}
extension SegmentedView: UICollectionViewDataSource {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return knowledge.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cellId", for: indexPath) as! SegmentedCell
let item = knowledge[indexPath.item]
cell.nameLabel.text = item
return cell
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
selectedMenu = CGFloat(indexPath.item) * frame.width
}
}
// This from my SegmentedViewController
class SegmentedViewController: UIViewController {
#IBOutlet weak var collectionView: UICollectionView!
#IBOutlet weak var segmentedViews: SegmentedView!
let cellId = "assesmentCell"
let colors: [UIColor] = [UIColor.blue, UIColor.yellow, UIColor.green]
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
setupCollection()
}
func scrollViewDidScroll(_ scrollView: UIScrollView) {
print(scrollView.contentOffset.x / 3)
segmentedViews.selectedMenu = scrollView.contentOffset.x / 3
}
func setupCollection() {
if let flowLayout = collectionView.collectionViewLayout as? UICollectionViewFlowLayout {
flowLayout.scrollDirection = .horizontal
flowLayout.minimumLineSpacing = 0
}
collectionView.register(UICollectionViewCell.self, forCellWithReuseIdentifier: cellId)
collectionView.dataSource = self
collectionView.delegate = self
collectionView.isPagingEnabled = true
}
}
thank you.

Answer 1

Your selectedMenu property does not listen for an event with the didSet property observer. So when you set selectedMenu in scrollViewDidScroll, nothing happens.
It may be a solution:
var selectedMenu: CGFloat? {
didSet {
collectionView.selectItem(at: <#T##IndexPath?#>, animated: <#T##Bool#>, scrollPosition: <#T##UICollectionView.ScrollPosition#>)
}
}
But be careful with the collectionView(_:didSelectItemAt:) method of SegmentedView, it can bring some unwanted behaviors. You can use a delegate pattern to trigger the method in another class.