uni-app 底部导航栏tabBar的使用相关

参考：

（1）https://blog.youkuaiyun.com/qq_37303018/article/details/84061322?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-2.compare&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-2.compare

（2）https://blog.youkuaiyun.com/woshidamimi0/article/details/102535243

（3）https://blog.youkuaiyun.com/weixin_44143975/article/details/88660866