uniapp小程序自定义tabbar

UniApp小程序支持自定义TabBar，可以通过以下步骤实现：

1. 在 `manifest.json` 文件中设置 `tabBar` 字段，例如：

"tabBar": {
  "color": "#666",
  "selectedColor": "#007aff",
  "backgroundColor": "#fff",
  "list": [
    {
      "pagePath": "pages/index/index",
      "text": "首页",
      "iconPath": "static/tabbar/home.png",
      "selectedIconPath": "static/tabbar/home-selected.png"
    },
    {
      "pagePath": "pages/cart/cart",
      "text": "购物车",
      "iconPath": "static/tabbar/cart.png",
      "selectedIconPath": "static/tabbar/cart-selected.png"
    },
    {
      "pagePath": "pages/profile/profile",
      "text": "我的",
      "iconPath": "static/tabbar/profile.png",
      "selectedIconPath": "static/tabbar/profile-selected.png"
    }
  ]
}

2. 在 `App.vue` 中添加 `tabBar` 组件，例如：

<template>
  <div>
    <tab-bar></tab-bar>
    <router-view></router-view>
  </div>
</template>

<script>
import TabBar from '@/components/TabBar.vue'

export default {
  components: {
    TabBar
  }
}
</script>

3. 在 `TabBar.vue` 组件中实现自定义的 TabBar 样式和交互，例如：

<template>
  <div class="tab-bar">
    <div
      v-for="(item, index) in list"
      :key="index"
      class="tab-bar-item"
      :class="{active: index === selected}"
      @click="onTabClick(index)"
    >
      <img :src="index === selected ? item.selectedIconPath : item.iconPath" alt="">
      <span>{{ item.text }}</span>
    </div>
  </div>
</template>

<script>
export default {
  props: {
    list: {
      type: Array,
      required: true
    },
    selected: {
      type: Number,
      required: true
    }
  },
  methods: {
    onTabClick(index) {
      if (index !== this.selected) {
        uni.switchTab({
          url: this.list[index].pagePath
        })
      }
    }
  }
}
</script>

<style scoped>
.tab-bar {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  display: flex;
  justify-content: space-around;
  align-items: center;
  height: 50px;
  background-color: #fff;
  box-shadow: 0 -1px 10px rgba(0, 0, 0, .1);
}

.tab-bar-item {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  font-size: 14px;
  color: #666;
}

.tab-bar-item img {
  width: 24px;
  height: 24px;
  margin-bottom: 4px;
}

.tab-bar-item.active {
  color: #007aff;
}
</style>

这样就可以实现自定义的 TabBar 了。需要注意的是，使用自定义的 TabBar 后，原生的 TabBar 将不再显示。