Keep a reference to UICollectionView header

Question

I need to store a view to use as a UICollectionView header. I don't want it to cycle out of memory though, because it needs to keep its state/data, etc.

With a table view you can just do tableView.tableHeaderView = view.

Here's what I'm trying:

func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {

        switch kind {
        case MagazineLayout.SupplementaryViewKind.sectionHeader:
            if let t = headerView { //headerView is an instance var
                return t
            } else {
                let view = collectionView.dequeueReusableSupplementaryView(ofKind: MagazineLayout.SupplementaryViewKind.sectionHeader, withReuseIdentifier: "MyHeaderView", for: indexPath) as! MyHeaderView
                view.titleLabel.text = "test"
                view.switch.addAction(for: .valueChanged, { [weak self] in
                    self?.switchValueChanged()
                })
                headerView = view
                return view
            }
        ...
    }

I don't want to re-create it every time the user scrolls it away and then back, so I'm trying to store a reference to it. This isn't working though. Hard to explain but the view it displays is cut off and the switch isn't responsive. If I comment out the "if" part and just create a new one every time, it looks correct but state is lost (i.e. the switch gets turned off) What's the best way to do this?

Answer 1

Since you're keeping the reference and not letting it deallocate when it scrolls out of the view, remove the register and dequeuing entirely. It worked fine for me, here's how:

let view = MyHeaderView()
override func viewDidLoad() {
    super.viewDidLoad()
    view.titleLabel.text = "test"
    view.switch.addAction(for: .valueChanged, { [weak self] in
        self?.switchValueChanged()
    })
}
func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
    switch kind {
    case MagazineLayout.SupplementaryViewKind.sectionHeader:
        return view
        //...
    }
}