1

警告： The item width must be less than the width of the UICollectionView minus the section insets left and right values, minus the content insets left and right values.

代码：

extension SaleViewController {
    override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator){
        checkEstimatedSize()
    }

    func checkEstimatedSize(){
        if(DeviceType.IS_IPAD || UIDevice.current.orientation == .landscapeLeft || UIDevice.current.orientation == .landscapeRight){
            if let layout = myCollectionView.collectionViewLayout as? UICollectionViewFlowLayout {
                layout.estimatedItemSize = CGSize(width: 1, height: 1)
                layout.invalidateLayout()
            }
        }else{
            if let layout = myCollectionView.collectionViewLayout as? UICollectionViewFlowLayout {
                layout.estimatedItemSize = UICollectionViewFlowLayoutAutomaticSize
                layout.invalidateLayout()
            }
        }
    }
}

我不确定问题出在哪里......它在 iPad 上有UICollectionViewFlowLayoutAutomaticSize和。wrap_content错误听起来像UICollectionViewFlowLayoutAutomaticSize；它有时会起作用。当它这样做时，完美地工作。如果没有，它会冻结并按如下方式填充日志：

The relevant UICollectionViewFlowLayout instance is <UICollectionViewFlowLayout: 0x10313a9a0>, and it is attached to <UICollectionView: 0x104096e00; frame = (10 138; 300 420); clipsToBounds = YES; autoresize = RM+BM; gestureRecognizers = <NSArray: 0x1c0458750>; layer = <CALayer: 0x1c02254e0>; contentOffset: {0, 0}; contentSize: {300, 220}; adjustedContentInset: {0, 0, 0, 0}> collection view layout: <UICollectionViewFlowLayout: 0x10313a9a0>. 2018-10-04 11:03:35.869371-0500 MyApp[276:5353] Make a symbolic breakpoint at UICollectionViewFlowLayoutBreakForInvalidSizes to catch this in the debugger. 2018-10-04 11:03:35.869398-0500 MyApp[276:5353] The behavior of the UICollectionViewFlowLayout is not defined because: 2018-10-04 11:03:35.869445-0500 MyApp[276:5353] the item width must be less than the width of the UICollectionView minus the section insets left and right values, minus the content insets left and right values. 2018-10-04 11:03:35.869555-0500 MyApp[276:5353] Please check the values returned by the delegate.

基本上，它一遍又一遍地重复相同的日志。

先感谢您。

4

1 回答 1

6

出现您的问题是因为参考width大于您的“工作”宽度collectionView

要解决此问题，您必须正确计算单元格参考大小。

您正在使用UICollectionViewFlowLayout，因此您可以利用UICollectionViewDelegateFlowLayout并实现以下方法（它是为单元格具有全屏width和动态高度的情况提供的）：

        /// UICollectionViewDelegateFlowLayout
        func collectionView(_ collectionView: UICollectionView,
                            layout collectionViewLayout: UICollectionViewLayout,
                            sizeForItemAt indexPath: IndexPath) -> CGSize {
            var referenceHeight: CGFloat = 54.0 // Approximate height of the cell
            // Cell width calculation
            let sectionInset = (collectionViewLayout as! UICollectionViewFlowLayout).sectionInset
            let referenceWidth = collectionView.safeAreaLayoutGuide.layoutFrame.width
                - sectionInset.left
                - sectionInset.right
                - collectionView.contentInset.left
                - collectionView.contentInset.right

                return CGSize(width: referenceWidth, height: referenceHeight)
            }
        }

请记住，如果您使用多列，则应width相应地计算单元格，并minInteritemSpacing应予以考虑。希望能帮助到你。

于 2018-11-20T12:09:33.907 回答