UICollectionView header dynamic height using Auto Layout

Question

I have a UICollectionView with a header of type UICollectionReusableView.

In it, I have a label whose length varies by user input.

Answer 1

@Pim's answer worked for me but as @linus_hologram in the comment section mentioned this solution makes AutoLayout complain about unsatisfiable constraints. I found a simple workaround:

In collectionView(_:layout:referenceSizeForHeaderInSection:) instead of getting a reference to the view that your instance of UICollectionView wants to reuse using collectionView(_:viewForSupplementaryElementOfKind:at:) just create an instance of your header view class on the fly and add a width constraint so that AutoLayout will be able to calculate your header's width:

let headerView = YourCustomHeaderClass() 
headerView.translatesAutoresizingMaskIntoConstraints = false
headerView.widthAnchor.constraint(equalToConstant: collectionView.frame.width).isActive = true
let size headerView.systemLayoutSizeFitting(UIView.layoutFittingCompressedSize)
                    return size
return size