Код: Выделить всё
NSLayoutConstraint.activate([
collectionView.topAnchor.constraint(equalTo: view.topAnchor),
collectionView.bottomAnchor.constraint(equalTo: view.keyboardLayoutGuide.topAnchor),
collectionView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
collectionView.trailingAnchor.constraint(equalTo: view.trailingAnchor)
])

Подробнее здесь: https://stackoverflow.com/questions/738 ... ayoutguide