Better location handling on map

frontend/lib/pages/settings.dart

@@ -7,7 +7,6 @@ import 'package:url_launcher/url_launcher.dart';
 
 
 bool debugMode = false;
-bool useLocation = false;
 
 class SettingsPage extends StatefulWidget {
   @override
@@ -15,7 +14,6 @@ class SettingsPage extends StatefulWidget {
 }
 
 class _SettingsPageState extends State<SettingsPage> {
-
   @override
   Widget build(BuildContext context) {
     return ListView(
@@ -90,6 +88,7 @@ class _SettingsPageState extends State<SettingsPage> {
       ],
     );
   }
+
   Widget darkMode() {
     return Row(
       children: [
@@ -115,46 +114,58 @@ class _SettingsPageState extends State<SettingsPage> {
       ],
     );
   }
+
   Widget setLocationUsage() {
+    Future<SharedPreferences> preferences = SharedPreferences.getInstance();
     return Row(
       children: [
         Text('Use location services'),
         // white space
         Spacer(),
-        Switch(
-          value: useLocation,
-          onChanged: (bool? newValue) async {
-            await Permission.locationWhenInUse
-              .onDeniedCallback(() {
-                rootScaffoldMessengerKey.currentState!.showSnackBar(
-                  SnackBar(content: Text('Location services are required for this feature'))
-                );
-              })
-              .onGrantedCallback(() {
-                rootScaffoldMessengerKey.currentState!.showSnackBar(
-                  SnackBar(content: Text('Location services are now enabled'))
-                );
-                setState(() {
-                  useLocation = newValue!;
-                });
-                SharedPreferences.getInstance().then(
-                  (SharedPreferences prefs) {
-                    prefs.setBool('useLocation', useLocation);
-                  }
-                );
-              })
-              .onPermanentlyDeniedCallback(() {
-                rootScaffoldMessengerKey.currentState!.showSnackBar(
-                  SnackBar(content: Text('Location services are required for this feature'))
-                );
-              })  
-            .request();
+        FutureBuilder(
+          future: preferences,
+          builder: (context, snapshot) {
+            if (snapshot.hasData) {
+              bool useLocation = snapshot.data!.getBool('useLocation') ?? false;
+              return Switch(
+                value: useLocation,
+                onChanged: setUseLocation,
+              );
+            } else {
+              return CircularProgressIndicator();
+            }
           }
         )
       ],
     );
   }
 
+  void setUseLocation(bool newValue) async {
+    await Permission.locationWhenInUse
+      .onDeniedCallback(() {
+        rootScaffoldMessengerKey.currentState!.showSnackBar(
+          SnackBar(content: Text('Location services are required for this feature'))
+        );
+      })
+      .onGrantedCallback(() {
+        rootScaffoldMessengerKey.currentState!.showSnackBar(
+          SnackBar(content: Text('Location services are now enabled'))
+        );
+        SharedPreferences.getInstance().then(
+          (SharedPreferences prefs) {
+            setState(() {
+              prefs.setBool('useLocation', newValue);
+            });
+          }
+        );
+      })
+      .onPermanentlyDeniedCallback(() {
+        rootScaffoldMessengerKey.currentState!.showSnackBar(
+          SnackBar(content: Text('Location services are required for this feature'))
+        );
+      })  
+    .request();
+  }
 
   Widget privacyInfo() {
     return Center(
@@ -163,8 +174,8 @@ class _SettingsPageState extends State<SettingsPage> {
           Text('Our privacy policy is available under:'),
           
           TextButton.icon(
-            icon: Icon(Icons.info),
-            label: Text(PRIVACY_URL),
+            icon: Icon(Icons.info, color: Colors.white),
+            label: Text(PRIVACY_URL, style: TextStyle(color: Colors.white)),
             onPressed: () async{
               await launchUrl(Uri.parse(PRIVACY_URL));
             }