A collection view that has intrinsic content size is its content size

ContentSizeCollectionView.swift

class ContentSizeCollectionView: UICollectionView {
    var contentSizeObservation: NSKeyValueObservation?
    
    override var intrinsicContentSize: CGSize {
        return shouldFullSize ? contentSizeWithInset : CGSize(width: UIView.noIntrinsicMetric, height: UIView.noIntrinsicMetric)
    }
    
    var shouldFullSize: Bool = true {
        didSet {
            invalidateIntrinsicContentSize()
        }
    }
    
    private var contentSizeWithInset: CGSize {
        let heightInset = contentInset.top + contentInset.bottom
        let widthInset = contentInset.left + contentInset.right
        return CGSize(width: contentSize.width + widthInset,
                      height: contentSize.height + heightInset)
    }
    
    required init?(coder: NSCoder) {
        super.init(coder: coder)
        
        contentSizeObservation = observe(\.contentSize) { [unowned self] (_, _) in
            self.invalidateIntrinsicContentSize()
        }
    }
    
    override func willMove(toSuperview newSuperview: UIView?) {
        if newSuperview == nil {
            contentSizeObservation?.invalidate()
        }
    }
}