IOS, swift - UICollectionReusableView not working

Question

I want to make collection view header but it isn't working.

Storyboard

On device

My code below is not working, print("ssssss") don't show.

override func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
        print("sssssss")
        switch kind {

        case UICollectionElementKindSectionHeader:

            let headerView = collectionView.dequeueReusableSupplementaryView(ofKind: kind,
                                                                             withReuseIdentifier: "mypageheader",
                                                                             for: indexPath) as! MyPageHeaderView
            headerView.backgroundColor = UIColor.blue;
            return headerView

        default:

            assert(false, "Unexpected element kind")
        }
    }

on viewDidLoad()

self.collectionView?.register(MyPageViewController.self,forSupplementaryViewOfKind: UICollectionElementKindSectionHeader,withReuseIdentifier: "mypageheader")

Answer 1

You should implement this delegate method:

func collectionView(_ collectionView: UICollectionView,
                    layout collectionViewLayout: UICollectionViewLayout,
                    referenceSizeForHeaderInSection section: Int) -> CGSize {

    return CGSize(width: collectionView.bounds.width, height: 100)
}

Don't forget to setup the delegate of your collectionView in the storyboard!