fix(iOS 26, Stack v4): fix workaround for RNSScreen being partially obstructed by UINavigationBar on iOS 26 Paper

[kligarski]

Description

Fixes the workaround from #3111 on Paper.

On Paper, in debug mode, sometimes there are some views between RNSScreenView and RNSScreenContentWrapper. This has been an issue before: #2683.

To make the workaround work correctly, we look for RNSScreenContentWrapper in first descendant chain, when in debug mode on Paper.

Fixes https://github.com/software-mansion/react-native-screens-labs/issues/412.

Changes

• look for RNSScreenContentWrapper in first descendant chain, when in debug mode on Paper

Test code and steps to reproduce

Run Test3111 on Paper in debug mode.

Checklist

• Included code example that can be used to test this change
• Updated TS types
• Updated documentation:
  • https://github.com/software-mansion/react-native-screens/blob/main/guides/GUIDE_FOR_LIBRARY_AUTHORS.md
  • https://github.com/software-mansion/react-native-screens/blob/main/native-stack/README.md
  • https://github.com/software-mansion/react-native-screens/blob/main/src/types.tsx
  • https://github.com/software-mansion/react-native-screens/blob/main/src/native-stack/types.tsx
• Ensured that CI passes

[kligarski]

This logic is similar to RNSScrollViewFinder, we could extract it to separate class but we would probably need to cast the result in places where we would use this function or provide wrappers. I also think that RNSScrollViewFinder might soon need to use more complicated logic. Let me know what you think.

[kligarski]

We can also use this logic for all cases, not only for Paper in debug mode, but it seemed like an overkill for getting first child.

[kmichalikk]

We could also just do:

RNSScreenContentWrapper *contentWrapper = nil;
UIView *currentView = vc.view;
while ([currentView.subviews count] > 0) {
    currentView = currentView.subviews[0];
    if ([currentView isKindOfClass:RNSScreenContentWrapper.class]) {
        contentWrapper = static_cast<RNSScreenContentWrapper *>(currentView);
        break;
    }
}

performance difference will be negligible (especially if we expect the class to be correct) and it improves readability.

[kmichalikk]

One issue I found

on Paper, ScrollView overflows below the screen

[kmichalikk]

We could also just do:

RNSScreenContentWrapper *contentWrapper = nil;
UIView *currentView = vc.view;
while ([currentView.subviews count] > 0) {
    currentView = currentView.subviews[0];
    if ([currentView isKindOfClass:RNSScreenContentWrapper.class]) {
        contentWrapper = static_cast<RNSScreenContentWrapper *>(currentView);
        break;
    }
}

performance difference will be negligible (especially if we expect the class to be correct) and it improves readability.