swift - 未调用 UICollectionView insetForSectionAtIndex

Question

我有一个具有以下声明和构造函数的类:

class GameView: UIView, UICollectionViewDelegate,  UICollectionViewDataSource, UICollectionViewDelegateFlowLayout
{
    var collectionView: UICollectionView?
    var flowLayout =  UICollectionViewFlowLayout()

    init (frame : CGRect, navigationController:UINavigationController, parentViewController: ScrambleViewController)
{
    super.init(frame : frame)
    cvFrame = CGRect(x: cvLeftBorder, y: cvY, width: Int(UIScreen.main.bounds.width) -  (2 * cvLeftBorder), height: cvHeight)
    collectionView = UICollectionView(frame: cvFrame!, collectionViewLayout: flowLayout);
    collectionView!.dataSource = self
    collectionView!.delegate = self;
    .....
}

这是一个每轮都有不同数量的单元格的游戏。我想将单元格居中，所以我插入了:

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

 // calculate the insets and return a UIEdgeInsets
}

由于某种原因，该函数从未被调用。否则，该程序运行良好。或者是否有更好的方法使每一轮的细胞居中？

提前致谢。

Answer 1

这会起作用:

@objc(collectionView:layout:insetForSectionAtIndex:)  func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets{
    return UIEdgeInsetsMake(5, 5, 5, 5)
}