criado o modelo city_load_model.dart a tela login_load_screen.dart e sync_unit_screen.dart

lib/widgets/dropdown_button_city.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:rkm/widgets/text_default.dart';
 
+import '../models/city_load_model.dart';
 import '../utils/color_palette.dart';
 import '../utils/const_variable.dart';
 
@@ -36,13 +37,13 @@ class DropDownButtonCity extends StatelessWidget {
               color: ColorPalette.white
           ),
           child: DropdownButtonHideUnderline(
-            child: DropdownButton<String>(
+            child: DropdownButton(
                 hint: TextDefault(text: 'Cidade',fontSize: ConstVariable().fontSizeInput),
                 value: select,
                 items: ConstVariable().itensCity.map((value) => DropdownMenuItem(
-                  value: value,
+                  value: value.nameCityFront,
                   child: TextDefault(
-                    text: value,
+                    text: value.nameCityFront,
                   ),
                 )
                 ).toList(),