横向模式下的Swift Collection View

Question

So i'm building an app where i have a collection view with 2 cells in a row. But when i rotate my screen i want to change that for example to 4. How do i do that?

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    let cellWidth =  (view.frame.size.width - 50) / 2
    return CGSize(width: cellWidth, height: cellWidth)
}

override func viewWillTransition(to size: CGSize,
                                 with coordinator: UIViewControllerTransitionCoordinator)
{
    collectionView?.collectionViewLayout.invalidateLayout()
}

Answer 1

Add super method in viewWillTransition .

super.viewWillTransition(to: size, with: coordinator)

This will allow the superview to pass this method class to all of its subviews.

override func viewWillTransition(to size: CGSize,
                             with coordinator: UIViewControllerTransitionCoordinator)
{
      super.viewWillTransition(to: size, with: coordinator)
      collectionView?.collectionViewLayout.invalidateLayout()
}

Answer 2

This code helped me in my problem.

func collectionView(_ collectionView: UICollectionView,
                    layout collectionViewLayout: UICollectionViewLayout,
                    sizeForItemAt indexPath: IndexPath) -> CGSize {
    let cellWidth =  (view.frame.size.width - 50) / 2
    if UIDevice.current.orientation.isLandscape {
        return CGSize(width: (cellWidth-30)/2, height: (cellWidth-30)/2)
    } else {
        return CGSize(width: cellWidth, height: cellWidth)
    }
}