custom-selected-background-of-selected-row-in-NSTableView.swift

import SwiftUI

struct NSTableViewWrapper: NSViewRepresentable {
    
    class Coordinator: NSObject, NSTableViewDataSource, NSTableViewDelegate {
        var parent: NSTableViewWrapper

        init(parent: NSTableViewWrapper) {
            self.parent = parent
        }

        func numberOfRows(in tableView: NSTableView) -> Int { 1 }

        func tableView(_ tableView: NSTableView, viewFor tableColumn: NSTableColumn?, row: Int) -> NSView? {
            let rowView = NSTableRowView()
            let textField = NSTextField(labelWithString: "Item")
            textField.isEditable = false
            textField.isBordered = false
            textField.backgroundColor = .clear
            textField.drawsBackground = false
            rowView.addSubview(textField)
            tableView.selectionHighlightStyle = .none
            return rowView
        }

        func tableView(_ tableView: NSTableView, rowActionsForRow row: Int, edge: NSTableView.RowActionEdge) -> [NSTableViewRowAction] {
            return [NSTableViewRowAction(style: .destructive, title: "Delete") { _, _ in }]
        }
        
        func tableViewSelectionDidChange(_ notification: Notification) {
            guard let tableView = notification.object as? NSTableView else { return }
            
            guard tableView.selectedRow >= 0 else {
                for i in 0..<tableView.numberOfRows {
                    guard let rowView = tableView.rowView(atRow: i, makeIfNecessary: false) else {
                        return
                    }
                    rowView.backgroundColor = .clear
                }

                return
            }
            
            guard let rowView = tableView.rowView(atRow: tableView.selectedRow, makeIfNecessary: false) else {
                return
            }
            rowView.backgroundColor = .red.withAlphaComponent(0.1)
        }
    }

    func makeCoordinator() -> Coordinator {
        return Coordinator(parent: self)
    }

    func makeNSView(context: Context) -> NSScrollView {
        let scrollView = NSScrollView()
        let tableView = NSTableView()
    
        let column = NSTableColumn(identifier: NSUserInterfaceItemIdentifier("Column"))
        tableView.addTableColumn(column)

        tableView.delegate = context.coordinator
        tableView.dataSource = context.coordinator

        scrollView.documentView = tableView

        return scrollView
    }

    func updateNSView(_ nsView: NSScrollView, context: Context) {
        (nsView.documentView as? NSTableView)?.reloadData()
    }
}

struct ContentView: View {
    var body: some View {
        NSTableViewWrapper()
    }
}