UICollectionReusableView method not being called

Question

I want my sections in the UICollectionView to have a header with an image.

I have followed these steps:

• at the storyboard, assigned a header a

Answer 1

Swift 4 Xcode 9.1 Beta 2

Add @objc

@objc func collectionView(_ collectionView: UICollectionView, layout  collectionViewLayout: UICollectionViewLayout, referenceSizeForFooterInSection section: Int) -> CGSize{
    let size = CGSize(width: 400, height: 50)
    return size
}

Credits: https://medium.com/@zonble/your-delegation-methods-might-not-be-called-in-swift-3-c6065ed7b4cd