localizeLabels crashes on iOS when SymbolLayer text-field expression contains null comparison

[Taharu]

Environment

• Xcode version: 16.4
• iOS version: 26.4
• Maps SDK Version: 11.24.0 via mapbox_maps_flutter 2.24.0

Observed behavior and steps to reproduce

On iOS, the app crashes when calling label localization via StyleManager.localizeLabels from mapbox_maps_flutter for a style that contains a SymbolLayer whose text-field expression includes a null comparison.

The same style does not crash on Android.

Problematic expression inside layout.text-field:

["!=", ["get", "hoge"], null]

Example error:

mapbox_maps_flutter/StyleController.swift:367: Fatal error: 'try!' expression unexpectedly raised an error: Swift.DecodingError.dataCorrupted(Swift.DecodingError.Context(codingPath: [RootCodingKeys(stringValue: "layout", intValue: nil), LayoutCodingKeys(stringValue: "text-field", intValue: nil)], debugDescription: "Failed to decode Value<String>", underlyingError: nil))

Expected behavior

The SDK should not crash when a valid Mapbox expression containing a null comparison is used inside a SymbolLayer text-field.

It should either handle the expression correctly during label localization or return a recoverable error instead of crashing.

[maios]

Hi @Taharu , thank you for reporting, we have created an internal issue to track this https://mapbox.atlassian.net/browse/MAPSIOS-2270

there will be changes made in how Maps iOS is decoding null value for StyleExpression, and how we apply localized label for symbol layer textField in the upcoming release. Meanwhile, I have a suggestion you could do for the expression so neither iOS and Android would crash - instead of using != and get expression, you could utilize has

textField: ["case", ["has", "hoge"], "A", "B"]