diff --git a/example/lib/main.dart b/example/lib/main.dart
index 966dfb52..18edb6dc 100644
--- a/example/lib/main.dart
+++ b/example/lib/main.dart
@@ -28,6 +28,8 @@ void main() {
 
 void initSDK() async {
   var options = EMOptions(appKey: 'easemob-demo#easeim');
+  options.deleteMessagesAsExitGroup = false;
+  options.deleteMessagesAsExitChatRoom = false;
   options.debugModel = true;
   options.enableAPNs("EaseIM_APNS_Product");
 
diff --git a/example/lib/pages/group/group_info_page.dart b/example/lib/pages/group/group_info_page.dart
index 8e33f352..5bf613bd 100644
--- a/example/lib/pages/group/group_info_page.dart
+++ b/example/lib/pages/group/group_info_page.dart
@@ -180,7 +180,7 @@ class GroupInfoPageState extends State<GroupInfoPage> {
     try {
       SmartDialog.showLoading(msg: '申请中...');
       if (_group != null) {
-        EMClient.getInstance.groupManager.requestToJoinPublicGroup(
+        await EMClient.getInstance.groupManager.requestToJoinPublicGroup(
           _group!.groupId,
         );
       }
diff --git a/ios/Classes/EMGroup+Flutter.m b/ios/Classes/EMGroup+Flutter.m
index b4b264c5..251a6028 100644
--- a/ios/Classes/EMGroup+Flutter.m
+++ b/ios/Classes/EMGroup+Flutter.m
@@ -27,7 +27,7 @@ - (NSDictionary *)toJson {
     ret[@"isAllMemberMuted"] = @(self.isMuteAllMembers);
     ret[@"options"] = [self.setting toJson];
     ret[@"permissionType"] = @([EMGroup premissionTypeToInt:self.permissionType]);
-    
+
     return ret;
 }
 
diff --git a/lib/src/models/em_message.dart b/lib/src/models/em_message.dart
index a4f81588..5d38a2d3 100644
--- a/lib/src/models/em_message.dart
+++ b/lib/src/models/em_message.dart
@@ -636,7 +636,7 @@ class EMFileMessageBody extends EMMessageBody {
   EMDownloadStatus fileStatus = EMDownloadStatus.PENDING;
 
   /// 文件大小
-  int? fileSize = 0;
+  int fileSize = 0;
 
   /// 文件名称
   String? displayName = '';