[New Architecture][iOS] Polygon/Geojson overlays never render with Google Maps (Fabric)

[ThomasPonzoVisma]

Summary

With the New Architecture (Fabric) enabled and provider="google" on iOS, <Polygon> and <Geojson> overlays never render. Markers in the same map render fine. The GMSPolygon is created but never attached to the map.

Environment

• react-native-maps: 1.27.2
• Platform: iOS, provider="google" (Google Maps SDK)
• New Architecture (Fabric): enabled
• React Native 0.83.x / Expo SDK 55

Reproduction

Minimal map with New Architecture enabled:

<MapView
  provider="google"
  style={{ flex: 1 }}
  initialRegion={{ latitude: 52.09, longitude: 5.12, latitudeDelta: 0.05, longitudeDelta: 0.05 }}
>
  <Polygon
    coordinates={[
      { latitude: 52.10, longitude: 5.10 },
      { latitude: 52.10, longitude: 5.14 },
      { latitude: 52.08, longitude: 5.12 },
    ]}
    fillColor="rgba(0,128,255,0.4)"
    strokeColor="#0066ff"
    strokeWidth={2}
  />
</MapView>

Expected: a filled triangle. Actual: nothing renders. (A <Marker> added to the same map does render.)

Root cause

In ios/AirGoogleMaps/AIRGoogleMap.mm, the New-Arch Google polygon branch of insertReactSubview: / removeReactSubview: leaves the attach/detach calls commented out, so the GMSPolygon is never assigned to the map:

} else if ([NSStringFromClass([subview class]) isEqualToString:@"RNMapsGooglePolygonView"]) {
//      RNMapsGooglePolygonView *polygon = (RNMapsGooglePolygonView*)subview;
//      [polygon didInsertInMap:self];   // <-- never attached → never renders
    [self.polygons addObject:subview];
}

RNMapsGooglePolygonView didInsertInMap: (which sets _view.map = map) is never invoked, and didRemoveFromMap is likewise never called on removal.

Note: attaching unconditionally is also unsafe under Fabric — coordinates can arrive via updateProps after mount, and attaching a GMSPolygon whose path has < 3 points crashes Google Maps (null-deref in gmssdk::CoordsToPoints during setMap:). So the attach must be deferred until the path is renderable.

Suggested fix

Invoke didInsertInMap: / didRemoveFromMap for the New-Arch polygon view, and defer the actual attach until the path is valid (≥ 3 points), re-checking from updateProps:

// AIRGoogleMap.mm — insertReactSubview: (and the mirror in removeReactSubview: → didRemoveFromMap)
if ([subview respondsToSelector:@selector(didInsertInMap:)]) {
    [subview performSelector:@selector(didInsertInMap:) withObject:self];
}

// RNMapsGooglePolygonView.mm
- (void)didInsertInMap:(AIRGoogleMap *)map { _pendingMap = map; [self attachIfReady]; }

- (void)attachIfReady {
    if (_view != nil && _view.map == nil && _pendingMap != nil
        && _view.path != nil && _view.path.count >= 3) {
        _view.map = _pendingMap;   // safe: path is renderable
    }
}
// ...and call [self attachIfReady] at the end of updateProps:, after coordinates are applied.

I have a complete, working patch-package patch against 1.27.2 for this (and several related New-Arch overlay issues) and am happy to open a PR if that's preferred.

Related: #5355 (Fabric support tracking), #5457.