Change NSTableView alternate row colors

Question

I\'m using the \"Alternating Rows\" option in Interface Builder to get alternating row colors on an NSTableView. Is there any way to change the colors of the alternating row

Answer 1

Swift 4+ version of AlternateRealist's answer:

public class AlternateBgColorTableView: NSTableView {
    var alternateBackgroundColor: NSColor? = .red

    override public func drawBackground(inClipRect clipRect: NSRect) {
        // If we didn't set the alternate color, fall back to the default behavior
        guard let alternateBackgroundColor = alternateBackgroundColor else {
            super.drawBackground(inClipRect: clipRect)

            return
        }

        // Fill in the background color
        backgroundColor.set()
        clipRect.fill()

        // Check if we should be drawing alternating colored rows
        if usesAlternatingRowBackgroundColors {
            // Set the alternating background color
            alternateBackgroundColor.set()

            // Go through all of the intersected rows and draw their rects
            var checkRect = bounds
            checkRect.origin.y = clipRect.origin.y
            checkRect.size.height = clipRect.height
            let rowsToDraw = rows(in: checkRect)
            var currentRow = rowsToDraw.location

            repeat {
                if currentRow % 2 != 0 {
                    // This is an alternate row
                    var rowRect = rect(ofRow: currentRow)
                    rowRect.origin.x = clipRect.origin.x
                    rowRect.size.width = clipRect.width
                    rowRect.fill()
                }

                currentRow += 1
            } while currentRow < rowsToDraw.location + rowsToDraw.length

            // Figure out the height of "off the table" rows
            var thisRowHeight = rowHeight

            if gridStyleMask.contains(.solidHorizontalGridLineMask) || gridStyleMask.contains(.dashedHorizontalGridLineMask) {
                thisRowHeight += 2 // Compensate for a grid
            }

            // Draw fake rows below the table's last row
            var virtualRowOrigin: CGFloat = 0
            var virtualRowNumber = numberOfRows

            if numberOfRows > 0 {
                let finalRect = rect(ofRow: numberOfRows - 1)
                virtualRowOrigin = finalRect.origin.y + finalRect.height
            }

            repeat {
                if virtualRowNumber % 2 != 0 {
                    // This is an alternate row
                    let virtualRowRect = NSRect(x: clipRect.origin.x, y: virtualRowOrigin, width: clipRect.width, height: thisRowHeight)
                    virtualRowRect.fill()
                }

                virtualRowNumber += 1
                virtualRowOrigin += thisRowHeight
            } while virtualRowOrigin < clipRect.origin.y + clipRect.size.height

            // Draw fake rows above the table's first row
            virtualRowOrigin = -1 * thisRowHeight
            virtualRowNumber = -1

            repeat {
                if abs(virtualRowNumber) % 2 != 0 {
                    // This is an alternate row
                    let virtualRowRect = NSRect(x: clipRect.origin.x, y: virtualRowOrigin, width: clipRect.width, height: thisRowHeight)
                    virtualRowRect.fill()
                }

                virtualRowNumber -= 1
                virtualRowOrigin -= thisRowHeight
            } while virtualRowOrigin + thisRowHeight > clipRect.origin.y
        }
    }
}