App crashes on controller.featuresAtPoint method

[BartoszStasiurka]

Platforms

iOS

Version of flutter-maplibre

0.3.0

Bug Description

When using a more complex map style in the example app, calling the controller.featuresAtPoint method causes the app to crash. The issue occurs after tapping on a map feature or city label, especially when the map is displaying land areas with detailed vector data.

Steps to Reproduce

1. Open feature_query_page.dart in the example app
2. Use a more complex map style, e.g. MapStyles.openMapTilesBright.uri
3. Run the app
4. Move the map over land and tap on a feature or city name

Expected Results

The app should return features at the tapped point without crashing.

Actual Results

The app crashes when tapping on some map feature.

Code Sample

MapLibreMap(
  options: MapOptions(
    initZoom: 7,
    initCenter: const Geographic(lon: 0.1, lat: 0.1),
    initStyle: MapStyles.openMapTilesBright.uri,
  ),

[josxha]

Thanks for the bug report @BartoszStasiurka - I'll look into it 👍🏼

edit: can reproduce the bug on the main branch.

[josxha]

I debugged the issue. The crash occurs in the featuresAtPoint and featuresInRect method when the used style uses numeric feature ids.

1. The convertion from NSNumber to dart has a flaw:

flutter-maplibre/lib/src/platform/ios/map_state.dart

Lines 202 to 204 in 501251f

	} else if (NSNumber.isInstance(object)) {
	return NSNumber.castFrom(object).intValue;
	}

2. The toDartMap() function from objective_c uses NSNumber::isFloatfrom objective_c that causes a crash:

flutter-maplibre/lib/src/platform/ios/map_state.dart

Lines 214 to 216 in 501251f

	properties: f.attributes.toDartMap().map(
	(k, v) => MapEntry(k.toString(), v),
	),

objective_c 8.1.0 contains a NSNumber bug that got solved in dart-lang/native#2581 and available in the 9.0.0-dev.0 prerelease. We can't use version 9.0.0-dev.0 because NSAttributedString is not available (dart-lang/native#2722). This problem is now fixed on their git repo but not released yet.

As a workaround I recommend to use the layerIds parameter for now with no numeric ids. We will have to wait for some upstream changes first.

[BartoszStasiurka]

Thanks for your response!