Add a simple UIView as header of UICollectionView

In swift like below

Register Header View

collectionView.register(HeaderView.self, forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader, withReuseIdentifier: "headerView")

In UICollectionViewDataSource

func collectionView(collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, atIndexPath indexPath: NSIndexPath) -> UICollectionReusableView {

    let headerView = collectionView.dequeueReusableSupplementaryViewOfKind(UICollectionElementKindSectionHeader, withReuseIdentifier: "headerView", forIndexPath: indexPath)

    headerView.frame.size.height = 100

    return headerView
}

Important is that you are supply the flow layout with the header size

flowLayout.headerReferenceSize = CGSize(width: self.collectionView.frame.size.width, height: 100)

Otherwise the data source method will not get called