Problem Loading Custom Style on iOS with maplibre_gl

[azertyuiop23]

Hello,

I am experiencing an issue with the Flutter package maplibre_gl. On Android, my custom style loads correctly from a local style.json file. However, on iOS, the same file does not load, and the map displays the default MapLibreStyles.demo style.

Details:
Code used to load the style:

String style = await rootBundle.loadString('assets/styles/style-default.json');
setState(() {
  _localStyle = style;
});

The style is then applied as follows:

MapLibreMap(
  styleString: _localStyle ?? '',
  // other parameters
);

My json file:

{
  "version": 8,
  "name": "my-style",
  "sources": {
    "osm": {
      "type": "raster",
      "tiles": [
        "https://mon-serveur.raster/tiles/{z}/{x}/{y}.png"
      ],
      "tileSize": 256
    },
    "mydata": {
      "type": "vector",
      "tiles": ["https://mon-serveur.mvt/tiles/{z}/{x}/{y}.mvt"],
      "minzoom": 2,
      "maxzoom": 22
    }
  },
  "layers": [
    {
      "id": "basemap",
      "type": "raster",
      "source": "osm"
    },
    {
      "id": "mydata-layer",
      "type": "circle",
      "source": "mydata",
      "minzoom": 2,
      "maxzoom": 22,
      "source-layer": "default",
      "paint": {
        "circle-radius": 7,
        "circle-color": "#FCD12A",
        "circle-stroke-color": "#FFFFFF",
        "circle-stroke-width": 1
      }
    }
  ]
}

Observations:

• On Android, the style loads and displays correctly.
• On iOS, the style does not load, and the default style is displayed.

Steps taken to resolve the issue:

• Verified the validity of the style.json file.
• Ensured the file is correctly included in the assets and referenced in pubspec.yaml.
• Checked the color formats in the style.json file.
• Attempted to load the style from an external URL.
• Reviewed iOS-specific permissions and configurations.
• Updated all dependencies to their latest stable versions.

Despite these efforts, the issue persist and I am not sure on the solution.

[azertyuiop23]

I finally found the cause of my problem. According to the package documentation, in the Map Styles section (see point 4), it is specified that it is only possible to provide the JSON content in raw form (in a String) on Android. In my code, I was using: rootBundle.loadString(...) to retrieve the style, which worked on Android but was problematic on iOS. So I realized that it wasn't necessary to wait for the style to be loaded in raw form for iOS. The solution is simply to specify the asset path directly in the styleString parameter, as follows:

MapLibreMap(
  styleString: “assets/styles/style-default.json”,
  // other parameters...
)

This modification solves the problem of displaying the style on iOS, which previously displayed the default style.