swift collection只有一个的时候居左

由于sectionInset与func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets { }协议相同，因此可以调用此协议来知道哪一部分仅剩一个单元。

您可以替换

flowLayout.sectionInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)

  func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {

    if collectionView.numberOfItems(inSection: section) == 1 {

         let flowLayout = collectionViewLayout as! UICollectionViewFlowLayout

        return UIEdgeInsets(top: 0, left: 0, bottom: 0, right: collectionView.frame.width - flowLayout.itemSize.width)

    }

    return UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)

}

效果