# Message receipts (/en/realtime-media/im/build/build-core-messaging/messages/message-receipts/ios) > For AI agents: see the complete documentation index at [llms.txt](/llms.txt). The Chat SDK provides the message read receipt feature that allows the user, after sending a message, to know whether the message is read. The feature is available to both one-to-one chats and group chats. * Message delivery receipt: Available only to one-to-one chats. * Message read receipt: Available to both one-to-one chats and group chats. ## Understand the tech [#understand-the-tech-1] The Chat SDK uses `IAgoraChatManager` to provide message receipt. The following are the core methods: * `AgoraChatOptions.enableRequireReadAck`: Enables message read receipt. * `AgoraChatOptions.enableDeliveryAck`: Enables message delivery receipt. * `ackConversationRead`: Sends a conversation read receipt. * `sendMessageReadAck`: Sends a message read receipt. * `sendGroupMessageReadAck`: Sends a message read receipt for group chat. The logic for implementing these receipts are as follows: * Message delivery receipts 1. The message sender enables delivery receipts by setting `AgoraChatOptions.enableDeliveryAck` as `YES`. 2. After the recipient receives the message, the SDK automatically sends a delivery receipt to the sender. 3. The sender receives the delivery receipt by listening for `messageDidDeliver`. * Conversation and message read receipts 1. The message sender enables read receipt by setting `AgoraChatOptions.enableRequireReadAck` as `YES`. 2. After reading the message, the recipient calls `ackConversationRead` or `sendMesageReadAck` to send a conversation or message read receipt. 3. The sender receives the conversation or message receipt by listening for `onConversationRead` or `messageDidRead`. ## Prerequisites [#prerequisites-1] Before proceeding, ensure that you meet the following requirements: * You have integrated the Chat SDK, initialized the SDK and implemented the functionality of registering accounts and login. For details, see [Chat SDK quickstart](../../../../get-started-sdk). * You understand the API call frequency limits as described in [Limitations](../../limitations). * Message read receipts for chat groups are not enabled by default. To use this feature, contact [support@agora.io](mailto\:support@agora.io). ## Implementation [#implementation-1] This section introduces how to implement message delivery and read receipts in your chat app. ### Message delivery receipts [#message-delivery-receipts-1] To send a message delivery receipt, take the following steps: 1. The message sender sets `enableDeliveryAck` in `AgoraChatOptions` as `YES` before sending the message: ```objc options.enableDeliveryAck = YES; ``` 2. Once the recipient receives the message, the SDK triggers `messageDidDeliver` on the message sender's client, notifying the message sender that the message has been delivered to the recipient. ```objc - (void)messagesDidDeliver:(NSArray *)aMessages { } [[AgoraChatClient sharedClient].chatManager removeDelegate:self]; ``` ### Conversation and message read receipts [#conversation-and-message-read-receipts-1] In both one-to-one chats and group chats, you can use message read receipts to notify the message sender that the message has been read. To minimize the method call for message read receipts, the SDK also supports conversation read receipts in one-to-one chats. #### One-to-one chats [#one-to-one-chats-1] In one-to-one chats, the SDK supports sending both the conversation read receipts and message read receipts. Agora recommends using conversation read receipts if the new message arrives when the message recipient has not entered the conversation UI. * Conversation read receipts Follow the steps to implement conversation read receipts in one-to-one chats. 1. When a user enters the conversation UI, check whether the conversation contains unread messages. If yes, call `ackConversationRead` to send a conversation read receipt. ```objc [[AgoraChatClient sharedClient].chatManager ackConversationRead:conversationId completion:nil]; ``` 2. The message sender listens for message events and receives the conversation read receipt in `onConversationRead`. ```objc - (void)onConversationRead:(NSString *)from to:(NSString *)to { // Add handling logics, for example, for refreshing the UI } ``` In use-cases where a user is logged in multiple devices, if the user sends a conversation read receipt from one device, the server sets the count of unread messages in the conversation as 0, and all the other devices receive `onConversationRead`. * Message read receipts To implement the message read receipt, take the following steps: 1. Send a conversation read receipt when the recipient enters the conversation. ```objc [[AgoraChatClient sharedClient].chatManager sendMessageReadAck:messageId toUser:conversationId completion:nil]; ``` 2. When a new message arrives, send the message read receipt and add proper handling logics for the different message types. ```objc // Occurs when the message is received. - (void)messagesDidReceive:(NSArray *)aMessages { for (AgoraChatMessage *message in aMessages) { // Sends a message read receipt [self sendReadAckForMessage:message]; } } - (void)sendReadAckForMessage:(AgoraChatMessage *)aMessage { // The received message if (aMessage.direction == AgoraChatMessageDirectionSend || aMessage.isReadAcked || aMessage.chatType != AgoraChatTypeChat) return; MessageBody *body = aMessage.body; // For audio, video, and file messages, send them after the user clicks the file. if (body.type == MessageBodyTypeFile || body.type == MessageBodyTypeVoice || body.type == MessageBodyTypeImage) return; [[AgoraChatClient sharedClient].chatManager sendMessageReadAck:aMessage.messageId toUser:aMessage.conversationId completion:nil]; } ``` 3. The message sender listens for the message receipt: ```objc // Occurs when the message read receipt is received - (void)messagesDidRead:(NSArray *)aMessages { for (AgoraChatMessage *message in aMessages) { // Adds handling logics } } ``` #### Chat groups [#chat-groups-1] For a group chat, group members can determine whether to require message read receipts when sending a message. If yes, after a group member reads the message, the SDK sends a read receipt. In a group chat, the number of message read receipts that are sent for the message refers to the number of group members that have read this message. The following table shows the restrictions of this feature: | Feature Restriction | Default | Description | | :------------------------------------------------------------------------------- | :----------------------------- | :----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Enabling the function | Disabled | To use this feature, contact [support@agora.io](mailto\:support@agora.io) to enable it. | | Permission | Group owner and administrators | By default, only the group owner and administrators can request read receipts when sending a message. You can contact [support@agora.io](mailto\:support@agora.io) to grant the permission to regular group members. | | Number of days before read receipts cannot be returned after the message is sent | 3 days | The server no longer records the group members that read the message three days after it is sent, nor sends the read receipts. | | Chat group size | 500 members | This feature is available only to groups with up to 500 members. In other words, each message in a group can have up to 500 read receipts. If the upper limit is exceeded, the latest read receipt record will overwrite the earliest one. | | Maximum number of group messages that can have read receipts per day | 500 | A group can have up to 500 messages each day for which read receipts can be returned. | Follow the steps to implement read receipts for a chat group message: 1. When sending a message, a group member can set whether to require a message read receipt. ```objc AgoraChatMessage *message = [[AgoraChatMessage alloc] initWithConversationID:to from:from to:to body:aBody ext:aExt]; message.isNeedGroupAck = YES; ``` 2. After the group member reads the chat group message, call `sendGroupMessageReadAck` from the group member's client to send a message read receipt: ```objc - (void)sendGroupMessageReadAck:(AgoraChatMessage *)msg { if (msg.isNeedGroupAck && !msg.isReadAcked) { [[AgoraChatClient sharedClient].chatManager sendGroupMessageReadAck:msg.messageId toGroup:msg.conversationId content:@"123" completion:^(AgoraChatError *error) { if (error) { } }]; } } ``` 3. The message sender listens for the message read receipt. ```objc // Occurs when the group message is received. - (void)groupMessageDidRead:(AgoraChatMessage *)aMessage groupAcks:(NSArray *)aGroupAcks { for (AgoraChatGroupMessageAck *messageAck in aGroupAcks) { //receive group message read ack } } ``` 4. The message sender can get the detailed information of the read receipt using `asyncFetchGroupMessageAcksFromServer`. ```objc // messageId: The message ID. // pageSize: The page size. The value range is [1,50]. // startGroupAckId: The starting receipt ID for query. Set it as nil or "" for the first call of the method and the SDK retrieves from the latest receipt. [[AgoraChatClient sharedClient].chatManager asyncFetchGroupMessageAcksFromServer:messageId groupId:groupId startGroupAckId:nil pageSize:pageSize completion:^(AgoraChatCursorResult *aResult, AgoraChatError *error, int totalCount) { // Add subsequent logics, for example, refreshing the UI }]; ```