問題：app.json使用以下程式碼，卻沒有如期望那樣在螢幕底部出現TabBar。

{
  "pages":[
    "pages/clickDemo/clickDemo",
    "pages/logs/logs",
    "pages/index/index",
    "pages/mypage/mypage"
  ],
  "window": {
    "backgroundTextStyle": "dark ",
    "navigationBarBackgroundColor": "#ddd",
    "navigationBarTitleText": "Tabbar Demo",
    "navigationBarTextStyle": "black",
    "backgroundColor": "#ff0000"
  },
  "tabBar": {
    "color": "#000000",
    "borderStyle": "#000",
    "selectedColor": "#9999FF",
    "list": [
      {
        "pagePath": "pages/index/index",
        "text": "首頁",
        "iconPath": "image/location_normal.png",
        "selectedIconPath": "image/location_selected.png"
      },
      {
        "pagePath": "pages/logs/logs",
        "text": "設定",
        "iconPath": "image/setting_normal.png",
        "selectedIconPath": "image/setting_selecred.png"
      }
    ]
  }
}