flutter_openim_sdk: ^1.0.4

  import 'package:flutter_openim_sdk/flutter_openim_sdk.dart';

// Initialize SDK
   OpenIM.iMManager
      ..initSDK(
        platform: IMPlatform.ios,
    	ipApi: 'Api interface address',
        ipWs: 'WebSocket address',
        dbPath: 'Database directory',
        listener: OnInitSDKListener(
          connecting: () {},
          connectFailed: (code, error) {},
          connectSuccess: () {},
          kickedOffline: () {},
          userSigExpired: () {},
          selfInfoUpdated: (user) {},
        ),
      )

      // Add message listener (remove when not in use)
      ..messageManager.addAdvancedMsgListener(OnAdvancedMsgListener(
        recvMessageRevoked: (id) {},
        recvC2CReadReceipt: (list) {},
        recvNewMessage: (msg) {},
      ))

      // Set up message sending progress listener
      ..messageManager.setMsgSendProgressListener(OnMsgSendProgressListener(
        progressCallback: (id, progress) {},
      ))

      // Set up friend relationship listener
      ..friendshipManager.setFriendshipListener(OnFriendshipListener(
        blackListAdd: (u) {},
        blackListDeleted: (u) {},
        friendApplicationListAccept: (u) {},
        friendApplicationListAdded: (u) {},
        friendApplicationListDeleted: (u) {},
        friendApplicationListReject: (u) {},
        friendInfoChanged: (u) {},
        friendListAdded: (u) {},
        friendListDeleted: (u) {},
      ))

      // Set up conversation listener
      ..conversationManager.setConversationListener(OnConversationListener(
        conversationChanged: (list) {},
        newConversation: (list) {},
        totalUnreadMsgCountChanged: (count) {},
        syncServerFailed: () {},
        syncServerFinish: () {},
        syncServerStart: () {},
      ))

      // Set up group listener
      ..groupManager.setGroupListener(OnGroupListener(
        applicationProcessed: (groupId, opUser, agreeOrReject, opReason) {},
        groupCreated: (groupId) {},
        groupInfoChanged: (groupId, info) {},
        memberEnter: (groupId, list) {},
        memberInvited: (groupId, opUser, list) {},
        memberKicked: (groupId, opUser, list) {},
        memberLeave: (groupId, info) {},
        receiveJoinApplication: (groupId, info, opReason) {},
      ));

 OpenIM.iMManager.login(uid: uid, token: token).then((value){
 	// login successful
 });

 OpenIM.iMManager.conversationManager.getAllConversationList().then((list) {
 	// Return to the conversation list
 });

 OpenIM.iMManager.friendshipManager.getFriendList().then((list) {
   	// Return to friends list
 });

List<Message> chatMsgList = List.empty(growable: true);
  
/// Custom message listener, the arrival of a new message will trigger the onNewMessage method callback
class CustomAdvancedMsgListener extends AdvancedMsgListener {
  final ValueChanged<Message>? onNewMessage;

  CustomAdvancedMsgListener({
    this.onNewMessage,
  });

  @override
  void onRecvNewMessage(Message msg) {
    if (null != onNewMessage) onNewMessage!(msg);
  }
}

  // If userID is not null and groupID is null, get a single chat message list
  // If the userID is null and the groupID is not null, get a group chat message list
  OpenIM.iMManager.messageManager.getHistoryMessageList(
          userID: uid,//User id
          startMsg: startMsg,//Last message, take chatMsgList[0]
          groupID: gid,//Group id
          count: 12,//Page Size
      )
      .then((list) => chatMsgList.addAll(list));
      

// Create a message listener
// After entering the chat page, you need to listen for new messages and then render the UI
// Each chat window has a unique uid (user id) or gid (group id)
// Determine whether the received message belongs to the current window according to uid or gid
var msgListener = CustomAdvancedMsgListener(onNewMessage: (message) {
     // If the sender user id is equal to the user id of the current chat page,
     // or the group id is equal to the current group id of the current chat page
     if (message.sendID == uid || message.groupID == gid) {
        if (!chatMsgList.contains(message)) {
	 			 // New message in current chat page
          chatMsgList.add(event.message);
        }
     }
});

// Add message listener
OpenIM.iMManager.messageManager.addAdvancedMsgListener(msgListener);

// Remove message monitoring
// After adding a message listener, if the page disposes, please remove the listener
// OpenIM.iMManager.messageManager.removeAdvancedMsgListener(msgListener);

// Create message
var message = await OpenIM.iMManager.messageManager.createTextMessage(
     text: 'I am the content of the message',
 );
// Send
OpenIM.iMManager.messageManager.sendMessage(
   message: message,
   onlineUserOnly: false,
   userID: uid, // Single chat value is not null
   groupID: gid, // The group chat value is not null
 ).then((v) {
   // Sent successfully
 }).catchError((e){
   // Failed to send
 });

OpenIM.iMManager.logout();