feat: 實作登出

點擊登出按鈕後刪除share preference 資料及跳轉回登入畫面

lib/PersonalInfo.dart

@@ -1,5 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
+import 'package:persistent_bottom_nav_bar_v2/persistent_bottom_nav_bar_v2.dart';
+import 'package:shared_preferences/shared_preferences.dart';
 import 'package:topic/BottomNavBar.dart';
 import 'package:topic/main.dart';
 import 'package:topic/HomePage.dart';
@@ -109,6 +111,19 @@ class _PersonalInfoState extends State<PersonalInfo> {
     }
   }
 
+  void _loginOut() async {
+    SharedPreferences prefs = await SharedPreferences.getInstance();
+    // remove all data in share preference(user data which save to identify user or others)
+    prefs.clear();
+    // navbar router setting
+    // replace screen with LoginPage and without navbar
+    pushReplacementWithoutNavBar(
+        context,
+        MaterialPageRoute(
+          builder: (context) => LoginPage(),
+        ));
+  }
+
   //頁面
   @override
   Widget build(BuildContext context) {
@@ -208,7 +223,9 @@ class _PersonalInfoState extends State<PersonalInfo> {
                   width: 60,
                 ),
                 ElevatedButton(
-                  onPressed: () {},
+                  onPressed: () {
+                    _loginOut();
+                  },
                   child: Text('登出'),
                   style: TextButton.styleFrom(
                     backgroundColor: Color(0xFFF5E3C3),