状态栏应用

1. 新建一个Application 为 App 的project

2. AppDelegate中添加代码 显示状态栏按钮

    statusBarItem = NSStatusBar.system.statusItem(withLength: NSStatusItem.squareLength) 
    statusBarItem.menu = menu
    statusBarItem.button?.image = NSImage(named: "settings")
    statusBarItem.button?.target = self
    statusBarItem.isVisible = true
   

3. info.plist Application is agent (UIElement) = YES 不显示在Dock

4. Main.storyboard 中的窗口删除 没有程序主窗口了