Question

您好我需要帮助通过UICollectionViewFlowLayout集中我的集合视图单元格。我的最终目标是让第一个细胞位于中间，让其他细胞在中间对齐。谢谢！

以下是现在的样子：

以及我希望它看起来像什么：

我找到了这个＆＃34;解决方案＆＃34;在SO但它似乎无法正常工作。

class CenterAlignedCollectionViewFlowLayout: UICollectionViewFlowLayout {

override func layoutAttributesForElementsInRect(rect: CGRect) -> [UICollectionViewLayoutAttributes]? {

    let attributes = super.layoutAttributesForElementsInRect(rect)

    // Constants
    let leftPadding: CGFloat = 8
    let interItemSpacing: CGFloat = 5

    // Tracking values
    var leftMargin: CGFloat = leftPadding // Modified to determine origin.x for each item
    var maxY: CGFloat = -1.0 // Modified to determine origin.y for each item
    var rowSizes: [[CGFloat]] = [] // Tracks the starting and ending x-values for the first and last item in the row
    var currentRow: Int = 0 // Tracks the current row
    attributes?.forEach { layoutAttribute in

        // Each layoutAttribute represents its own item
        if layoutAttribute.frame.origin.y >= maxY {

            // This layoutAttribute represents the left-most item in the row
            leftMargin = leftPadding

            // Register its origin.x in rowSizes for use later
            if rowSizes.count == 0 {
                // Add to first row
                rowSizes = [[leftMargin, 0]]
            } else {
                // Append a new row
                rowSizes.append([leftMargin, 0])
                currentRow += 1
            }
        }

        layoutAttribute.frame.origin.x = leftMargin

        leftMargin += layoutAttribute.frame.width + interItemSpacing
        maxY = max(layoutAttribute.frame.maxY, maxY)

        // Add right-most x value for last item in the row
        rowSizes[currentRow][1] = leftMargin - interItemSpacing
    }

    // At this point, all cells are left aligned
    // Reset tracking values and add extra left padding to center align entire row
    leftMargin = leftPadding
    maxY = -1.0
    currentRow = 0
    attributes?.forEach { layoutAttribute in

        // Each layoutAttribute is its own item
        if layoutAttribute.frame.origin.y >= maxY {

            // This layoutAttribute represents the left-most item in the row
            leftMargin = leftPadding

            // Need to bump it up by an appended margin
            let rowWidth = rowSizes[currentRow][1] - rowSizes[currentRow][0] // last.x - first.x
            let appendedMargin = (collectionView!.frame.width - leftPadding  - rowWidth - leftPadding) / 2
            leftMargin += appendedMargin

            currentRow += 1
        }

        layoutAttribute.frame.origin.x = leftMargin

        leftMargin += layoutAttribute.frame.width + interItemSpacing
        maxY = max(layoutAttribute.frame.maxY, maxY)
    }

    return attributes
}

Answer 1

确保您的视图控制器是集合视图的委托，并从UICollectionViewDelegateFlowLayout实现以下方法：

func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAtIndex section: Int) -> UIEdgeInsets {
    let sideInset = (collectionView.frame.size.width - myCollectionViewCellSize.width) / 2
    return UIEdgeInsets(top: 0, left: sideInset, bottom: 0, right: sideInset)
}

Answer 2

使用UICollectionViewDelegateFlowLayout，有方法collectionView：collectionViewLayout：sizeForItemAtIndexPath。

在那里你可以定义你想要多少边距（让我们说这个例子它是一个定义为10.0的变量），只需对你的宽度做一些计算：

let width = collectionView.frame.size.width - （margin * 2）

然后从那里返回你的宽度和身高的CGSize。

您的应用是否支持多种布局（纵向/横向以及iPad上的多任务处理）？不要忘记同时实现willTransitionToTraitCollection和viewWillTransitionToSize，因为你的视图宽度都会发生变化，你也应该更新你的单元格。

将容器中的UICollectionView单元居中

2 个答案: