[Swift]UICollectionViewでカレンダーUIを作った際に、行数で高さを動的に変えるポイント

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        let height = collectionView.collectionViewLayout.collectionViewContentSize.height
        if height != view.frame.size.height {
            heightConstraint = collectionView.heightAnchor.constraint(equalToConstant: height)
            heightConstraint?.isActive = true
            self.view.setNeedsLayout()
            self.view.layoutIfNeeded()
        }
    }

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        collectionView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
        collectionView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
        collectionView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
        collectionView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true

        if let height = heightConstraint {
            height.isActive = false
            heightConstraint = collectionView.heightAnchor.constraint(equalToConstant: collectionView.collectionViewLayout.collectionViewContentSize.height)
            heightConstraint!.isActive = true
        }
    }