隐藏默认NSOutlineView展开/折叠箭头

class CustomOutlineViewDelegate: NSObject, NSOutlineViewDelegate {
    func outlineView(_ outlineView: NSOutlineView, viewFor tableColumn: NSTableColumn?, item: Any) -> NSView? {
        let cellView = outlineView.makeView(withIdentifier: NSUserInterfaceItemIdentifier(rawValue: "CustomCell"), owner: self) as? NSTableCellView
        cellView?.imageView?.image = nil // 隐藏展开/折叠箭头
        return cellView
    }

    func outlineView(_ outlineView: NSOutlineView, rowViewForItem item: Any) -> NSTableRowView? {
        return CustomTableRowView()
    }
}

class CustomTableRowView: NSTableRowView {
    override init(frame frameRect: NSRect) {
        super.init(frame: frameRect)
        self.imageView?.image = nil // 隐藏展开/折叠箭头
    }

    required init?(coder decoder: NSCoder) {
        super.init(coder: decoder)
        self.imageView?.image = nil // 隐藏展开/折叠箭头
    }
    
    override func drawBackground(in dirtyRect: NSRect) {
        // 绘制自定义的背景颜色或样式
    }

    override func drawSelection(in dirtyRect: NSRect) {
        // 绘制自定义的选中样式
    }
}

// 在使用NSOutlineView的地方设置自定义的Delegate
let outlineView = NSOutlineView()
outlineView.delegate = CustomOutlineViewDelegate()