code: function showMenu () {
    const prompt = require('@system.prompt')
    const router = require('@system.router')
    const appInfo = require('@system.app').getInfo()
    prompt.showContextMenu({
      itemList: ['保存桌面', '关于', '取消'],
      success: function (ret) {
        switch (ret.index) {
        case 0:
          // 保存桌面
          createShortcut()
          break
        case 1:
          // 关于
          router.push({
            uri: '/About',
            params: {
              name: appInfo.name,
              icon: appInfo.icon
            }
          })
          break
        case 2:
          // 取消
          break
        default:
          prompt.showToast({
            message: 'error'
          })
        }
      }
    })
  }
docs: 显示菜单