ScrollView "StickyHeaderComponent" prop need documentation

[cheolhow]

Description

facebook/react-native#25428

I found StickyHeaderComponent is available in the latest version RN's ScrollView. But it's not documented.

What is the problem?

There is some ambiguity in understanding just as described in PR.
For example, if I use StickyHeaderComponent with stickyHeaderIndices, it's ambiguous how to handle it.
It similar to CellRenderComponent prop, but it doesn't keep the sticky behavior.

    const Test = styled.View`
      background-color: red;
    `;

    _renderStickyHeaderComponent = ({ children, ...props }) => {
        return <Test {...props}>{children}</Test>
    }

    <Animated.FlatList
        ...props
        stickyHeaderIndices={[1]}
        StickyHeaderComponent={this._renderStickyHeaderComponent}
    />

How can we address it?

Requires documentation and some use-case of StickyHeaderComponent prop

Why is it important?

As explained in the PR link above, the CellRenderComponent prop can not custom ScrollViewStickyHeader , but StickyHeaderComponent property can custom. So it makes us deal with the various situation.

Who needs this?

It's necessary for everyone. Especially for those who need to implement animation in ScrollView, FlatList.

[DZuz14]

@cheolhow You mention ScrollView in the title of the issue, but your code snippet is that of a FlatList? Which are you having a problem with?

[cheolhow]

@DZuz14 Flatlist is inherits VirtualizedList. And VirtualizedList is inherits ScrollView. Therefore, the issue of ScrollView can be described with FlatList.

[cheolhow]

When I check the ScrollView code, it seems that the StickyHeaderComponent property is completely replaced by a custom component.
I handled the code of the ScrollViewStickyHeader component by customizing the code to maintain the default sticky behavior. However, this process seems to be a temporary measure.
Discussion of improving this part will begin in the react-native repository.
However, it seems that the document still needs notation and explanation for this property.

[Simek]

The code, description and types for missing StickyHeaderComponent prop can be found here:

• https://github.com/facebook/react-native/blob/master/Libraries/Components/ScrollView/ScrollView.js#L521

It should be added to the ScrollView page.