尽管宽度相等，但集合视图网格的最后一行显示不同 - swift iOS [英] Collection view grid last row appears differently despite equal widths - swift iOS

问题描述

我有一个固定的集合视图单元格网格 (UICollectionView)，但底行中的单元格在屏幕上显示的宽度总是稍小.collectionViewLayout 中使用的框架大小(或边界)和计算宽度:UICollectionViewLayout sizeForItemAt 对所有行都相同.

I've a fixed grid of collection view cells (UICollectionView) but the cells in the bottom row always appears with a slightly smaller width on screen. The frame size (or bounds) and calculated width used within collectionViewLayout: UICollectionViewLayout sizeForItemAt are the same for all rows.

        func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize
{
    let settings = currentContents[indexPath.item]
    let height = CGFloat(30)

    // https://stackoverflow.com/questions/54915227/uicollectionview-remove-space-between-cells-with-7-items-per-row
    var cellWidth = CGFloat()
    let availableWidth = collectionView.bounds.size.width
    print("available width", availableWidth)
    let minimumWidth = floor(availableWidth / collectionContents.cellsPerRow5)
    print("minmum width", minimumWidth)
    cellWidth = minimumWidth * settings.portion - 1
    print("cell width", cellWidth)

    return CGSize(width: cellWidth, height: height)
}

我想让底行与其他行对齐，但无法想象在布局委托方法(或如何修复)中返回值后更改宽度的情况.

I'd like to get the bottom row to line up with the other rows, but can't imagine what is happening that is changing the widths after returning the value in the layout delegate method (or how to fix).

推荐答案

我发现的最好方法是在计算初始列宽后捕获剩余空间(减去 1 以避免四舍五入)，然后将剩余空间用于附加列.

The best way I found was to capture the remaining space (minus 1 to avoid rounding up) after calculating the initial column width, and then use this remaining space for additional columns.

对于两列示例:

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize
{
    if indexPath.item == 0 || indexPath.item == 1
    { rowHeight = 40 }
    else { rowHeight = 30 }
    var cellWidth = CGFloat()
    let minimumWidth = floor(availableWidth / numberOfColumns)
    var columnPortion = CGFloat()
    let columnNumber = indexPath.item % Int(numberOfColumns)
    switch columnNumber
    {
    case 0:
        columnPortion = columnPortion1
        cellWidth = minimumWidth * columnPortion - 10
        remainder = availableWidth - cellWidth - 1
    case 1:
        columnPortion = columnPortionFinal
        cellWidth = remainder
    default:
        break
    }
    return CGSize(width: cellWidth, height: rowHeight)
}

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