我尝试使用一些共享首选项方法，如setStringList和getStringList，但在使用get和显示其值时 我在控制台上看到下面这行代码：

{0: Instance of 'SearchDelegateModel', 1: Instance of 'SearchDelegateModel'}

下面是代码：

IconButton(
  icon: Icon(Icons.search),
  onPressed: () async {
    SharedPreferences prefs = await SharedPreferences.getInstance();

    final busqueda = await showSearch(context: context, delegate: SearchDelegateMenuPrincipal("Buscar...", this.historialMenuPrincipal));
    if (busqueda != null) {
      historialMenuPrincipal.removeWhere((item) => item.apodo == busqueda.apodo);
      this.historialMenuPrincipal.insert(0, busqueda);
      final historialbusquedacastead = historialMenuPrincipal.map((e) => e.toString()).toList();
      prefs.setStringList("HistorialBusquedaPreferences", historialbusquedacastead);
      var getpre = prefs.getStringList("HistorialBusquedaPreferences");
      print(getpre.asMap()); // the print shows {0: Instance of 'SearchDelegateModel', 1: Instance of 'SearchDelegateModel'}
    }
  },
),
//////////
List MenuPrincipalViewproductFromJson(String str) => List<SearchDelegateModel>.from(json.decode(str).map((x) => SearchDelegateModel.fromJson(x)));
 SearchDelegateModel{
 String apodo;
 String name;
SearchDelegateModel({this.apodo,this.name})
}
factory SearchDelegateModel.fromJson(Map<String, dynamic> parsedJson){
    return SearchDelegateModel(
name: parsedJson['name'],
        apodo : parsedJson['apodo'])}