如何在UICollectionView中找到与hICollectionView中的特定Cell相邻且水平相邻的Cell / IndexPath

Question

我想知道如何在UICollectionView中找到水平和垂直相邻或周围的单元格/ IndexPaths到特定（红色）单元格。

红细胞可能处于任何位置。

我可以找到红色单元格indexPath，它位于任何位置。

我附上此图片文件以更清楚我的问题。

任何帮助或想法将不胜感激。

Answer 1

算法

假设：

每行有四个单元格。

计算：

1. int rowCount = 4 //连续的单元格总数。正如你已经描述的那样。
2. int lastRow = totalCell / rowCount //最后一行。
3. int colNo = index % rowCount //列号，即此索引位于哪一列
4. int rowNo = index / rowCount //此索引位于哪一行

<强> ALGO

1. if `colNo == 0` // cell is the left most.
     if `rowNo == 0` // index of first row
        adjacent = index + 1, index + rowCount
     else if `rowNo == lastRow` // index of last row
        adjacent = index + 1, index - rowCount
     else 
        adjacent = index + 1, index - rowCount

2. if `colNo == 1` // cell is the second in its row .
     if `rowNo == 0` // index is at first row
        adjacent = index - 1, index + 1, index + rowCount
     else if `rowNo == lastRow` // index is at last row
        adjacent = index - 1 ,index + 1, index - rowCount
     else 
        adjacent = index + 1, index - rowCount, index - 1

3. if `colNo == 2` // cell is the third in row.
     if `rowNo == 0` // index of first row
        adjacent = index - 1, index + 1, index + rowCount
     else if `rowNo == lastRow` // index of last row
        adjacent = index - 1, index + 1, index - rowCount
     else 
        adjacent = index + 1, index - rowCount, index - 1

4. if `colNo == 3` // cell is the left most.
     if `rowNo == 0` // index of first row
        adjacent = index - 1, index + rowCount
     else if `rowNo == lastRow` // index of last row
        adjacent = index - 1, index - rowCount
     else 
        adjacent = index - 1, index - rowCount

Answer 2

我的解决方案不考虑任何间距或不同的单元格大小，但是为了让您了解它是如何工作的：

private func selectCellAndAdjacentCellsAtIndexPath(_ indexPath: IndexPath) {
    if let cell = collectionView?.cellForItem(at: indexPath) {
        var cellsToSelect: [UICollectionViewCell] = [cell]

        // get adjacent cells

        // top
        if let topIndexPath = collectionView?.indexPathForItem(at: CGPoint(x: cell.center.x, y: cell.center.y - cell.frame.height)), let topCell = collectionView?.cellForItem(at: topIndexPath) {
            cellsToSelect.append(topCell)
        }
        // left
        if let leftIndexPath = collectionView?.indexPathForItem(at: CGPoint(x: cell.center.x - cell.frame.width, y: cell.center.y)), let leftCell = collectionView?.cellForItem(at: leftIndexPath) {
            cellsToSelect.append(leftCell)
        }
        // bottom
        if let bottomIndexPath = collectionView?.indexPathForItem(at: CGPoint(x: cell.center.x, y: cell.center.y + cell.frame.height)), let bottomCell = collectionView?.cellForItem(at: bottomIndexPath) {
            cellsToSelect.append(bottomCell)
        }
        // right
        if let rightIndexPath = collectionView?.indexPathForItem(at: CGPoint(x: cell.center.x + cell.frame.width, y: cell.center.y)), let rightCell = collectionView?.cellForItem(at: rightIndexPath) {
            cellsToSelect.append(rightCell)
        }

        // select cells
        for cellToSelect in cellsToSelect {
            cellToSelect.backgroundColor = UIColor.lightGray
        }
    }
}

Answer 3

确定如果它们的大小相同，则说100x100，然后获取您选择的单元格

向collectionView询问单元格的CGRect

找到中心。

然后向collectionView询问点，x - 100，x + 100，y - 100，y + 100的单元格。

然后看哪些不是零？