todos-contra-el-fuego-mobile/lib/models/your_location_persist.dart

import 'dart:async';
import 'dart:convert';

// ignore: implementation_imports
import 'package:shared_preferences/src/shared_preferences_legacy.dart';

import '../globals.dart' as globals;
import 'your_location.dart';

const String locationKey = 'yourlocations';

Future<List<YourLocation>> loadYourLocations() async {
  return globals.prefs.then((SharedPreferences prefs) {
    final List<String>? yourLocations = prefs.getStringList(locationKey);
    final List<YourLocation> persistedList = <YourLocation>[];
    for (final String locationString in (yourLocations ?? <String>[])) {
      final Map<String, dynamic> locationMap =
          json.decode(locationString) as Map<String, dynamic>;
      persistedList.add(YourLocation.fromJson(locationMap));
    }
    return persistedList;
  });
}

void persistYourLocations(List<YourLocation> yl) {
  // debugPrint('Persisting $yl');
  globals.prefs.then((SharedPreferences prefs) {
    final List<String> ylAsString = <String>[];
    yl.whereType<YourLocation>().forEach((YourLocation location) {
      ylAsString.add(json.encode(location.toJson()));
    });
    prefs.setStringList(locationKey, ylAsString);
  });
}