The weex front end has custom components on the ios side, so why are the front end components still called on the iOS side?

There is a sentence in the official guide of

weex:
if you use tags or styles that are not supported by Weex when customizing components, you need to implement them in Android and iOS, otherwise it will result in rendering exception.
can"t really figure out what it means.
I defined a component in the weex project

<template>
  <div class="myClass">
    <button></button>
    <scroll></scroll>
  </div>
</template>

<script>
export default {
  name: "MyComponent"
}
</script>

<style scoped>
.myClass {
  background-color: blue;
  width: 375px;
  height: 300px;
}
</style>

customized a component in iOS

[WXSDKEngine registerComponent:@"MyComponent" withClass:NSClassFromString(@"MyComponent")];

then package the index.js file directly in weex < MyComponent > < / MyComponent > after running it. The component ios uses when downloading and parsing to this file is the custom component MyComponent in the weex project rather than the custom component in the ios project. If the weex project does not implement this custom component, the ios project run can achieve the desired effect to display ios custom components, but how to ensure the unity of the three ends?
the ios side calls the components on the iOS side, and the weex side calls the components on the weex side. How do you do this? The custom module also has the same confusion.
A custom module on the iOS side. Weex can directly use the method to call up the ios. However, if you register the module weex.registerModule in the weex, it is also the weex module code that keeps going when running on the iOS end, which is really incomprehensible.

Jul.18,2022
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