uniapp自定义导航栏 获取高度的方法

```javascript
	<view :style="{ paddingTop: statusBarHeight + 'px' }">
      <view
        :style="{ height: titleBarHeight + 'px', backgroundColor: 'red' }"
      ></view>
    </view>

data: {
  statusBarHeight: 0,
  titleBarHeight: 0,
}

onLoad() {
    const SystemInfo = wx.getSystemInfoSync();
    this.statusBarHeight = SystemInfo.statusBarHeight;
  },
  
  onReady() {
    this.titleBarHeight =
      (uni.getMenuButtonBoundingClientRect().top - this.statusBarHeight) * 2 +
      uni.getMenuButtonBoundingClientRect().height;
  },