无法在Cocoa Swift Mac OS中更改边框颜色

import Cocoa

class CustomView: NSView {
    override func draw(_ dirtyRect: NSRect) {
        super.draw(dirtyRect)
        
        // 设置边框颜色为红色
        let borderColor = NSColor.red
        
        // 创建一个矩形路径
        let path = NSBezierPath(rect: dirtyRect)
        
        // 设置边框线条宽度
        path.lineWidth = 2.0
        
        // 设置边框颜色
        borderColor.set()
        
        // 绘制边框路径
        path.stroke()
    }
}

// 在需要使用自定义边框颜色的地方，使用自定义视图类进行绘制
let customView = CustomView(frame: NSRect(x: 0, y: 0, width: 200, height: 200))
customView.wantsLayer = true
customView.layer?.backgroundColor = NSColor.white.cgColor

// 将自定义视图类添加到窗口中显示
let window = NSWindow(contentRect: NSRect(x: 0, y: 0, width: 800, height: 600), styleMask: .titled, backing: .buffered, defer: false)
window.contentView?.addSubview(customView)
window.makeKeyAndOrderFront(nil)