NSTableView 中每一行是用NSTableRowView表示的，因此可以繼承此類，重寫點擊時的drawSelection方法

示例更改了點擊時的行顏色，并且在最左邊畫了一條線：

class CSTableRowView: NSTableRowView {

    override func drawSelection(in dirtyRect: NSRect) {
        if self.selectionHighlightStyle != .none {
            // 填充背景顏色
            let fillColor = NSColor(red: 35.0/255, green: 63.0/255, blue: 95.0/255, alpha: 1)
            fillColor.set()
            dirtyRect.fill()
            // 繪制左側邊框
            let lineColor = NSColor(red: 0.20, green: 0.85, blue: 0.99, alpha: 1.00)
            lineColor.setFill()
            let lineRect = NSRect(x: 0, y: 0, width: 2, height: dirtyRect.height)
            lineRect.fill()
        }
    }
}

在代理方法中，使用自定義的 rowView
// 示例用的 outlineView

    func outlineView(_ outlineView: NSOutlineView, rowViewForItem item: Any) -> NSTableRowView? {
        var rowView = outlineView.makeView(withIdentifier: NSUserInterfaceItemIdentifier(rawValue: "rowView"), owner: self) as? CSTableRowView
        if rowView == nil {
            rowView = CSTableRowView()
            rowView?.identifier = NSUserInterfaceItemIdentifier(rawValue: "rowView")
        }
        return rowView
    }