Ios 横向模式下的Swift集合视图

因此，我正在构建一个应用程序，其中我有一个集合视图，一行有两个单元格。但当我旋转屏幕时，我想将其更改为4。我该怎么做

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()
}

在viewWillTransition中添加超级方法

这将允许superview将此方法类传递给其所有子视图

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

---

这个代码帮助我解决了我的问题

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)
    }
}

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)
    }
}