Swift - Change height of CollectionView Header - ios

Question

I would like to change the height of the header of my CollectionViewController.
I already know that I could use a code like that:
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
return CGSize(width: collectionView.frame.size.width, height: 250)
}
I would like to do that, but directly within the UICollectionReusableView (the header view).
Is there any function that allows that?

Answer 1

You'll need to add UICollectionViewDelegateFlowLayout.
class ViewController: UIViewController, UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
return CGSize(width: collectionView.frame.width, height: collectionView.frame.height)
}
}

Answer 2

To change header size dynamically, use headerReferenceSize UICollectionViewFlowLayout property.
let collectionViewLayout = UICollectionViewFlowLayout()
collectionViewLayout.headerReferenceSize = CGSize(width: view.frame.size.width, height: 80)
Make sure not to include referenceSizeForHeaderInSection delegate method to make it work.

Answer 3

Headers in collectionview are diferent like tableview because you need to create diferent kind of cell, this cell is named UICollectionReusableView, create a class with this name and then in your collectionview check this option:
enter image description here
and then you can call this on code with this function:
override func collectionView(_ collectionView: UICollectionView,
viewForSupplementaryElementOfKind kind: String,
at indexPath: IndexPath) -> UICollectionReusableView {
//1
switch kind {
//2
case UICollectionElementKindSectionHeader:
//3
let headerView = collectionView.dequeueReusableSupplementaryView(ofKind: kind,
withReuseIdentifier: "UICollectionReusableViewID",
for: indexPath) as! UICollectionReusableViewClass
//Customize
return headerView
default:
//4
assert(false, "Unexpected element kind")
}
}
all the credits RayWenderLich tutorials : https://www.raywenderlich.com/1404-uicollectionview-tutorial-reusable-views-selection-and-reordering