Displaying the Conversation List

After the user logs in to the app, the app can display a list of recent conversions like WeChat. The overall display process includes the following steps: pulling the conversation list, processing the change notifications, and updating the UI content (including the unread count). This document describes these steps in detail.

Pulling the conversation list

After logging in to the app, you can call getConversationList() to pull the local conversation list and display the list on the UI. The conversation list is a list of [V2TIMConversation]V2TIMConversation objects, and every object represents a conversation.

The number of local conversations may be large, even more than 500. Therefore, it may take a long time to load all conversations at once, which results in the slow display of the list on the UI. To improve the user experience, we provide the getConversationList() API to support pulling by page.

1. When the getConversationList() API is called for the first time, you can set the nextSeq parameter to 0, indicating that the conversation list is pulled from the beginning, and set count to 50, indicating that 50 conversation objects are pulled at a time.
2. The IM SDK pulls the conversation list in reverse chronological order. After the conversation list is pulled successfully for the first time, V2TIMConversationResult, which is the callback result of getConversationList(), will contain the nextSeq field for the next pulling by page operation and the isFinish field that indicates whether all conversation objects have been pulled.
   • If the returned value of isFinished is true, all conversations have been pulled.
   • If the returned value of isFinished is false, more conversations can be pulled. This does not mean that the next page of the conversation list will be pulled immediately. In common communications software, pulling by page is often triggered when the user swipes. Each time the user swipes on the conversation list, pulling by page is triggered once.
     
3. If the user continues to pull down the conversation list and the conversation list has content yet to be pulled, the SDK continues to call the getConversationList() API and passes in the nextSeq and count parameters again. The values of the two parameters come from the V2TIMConversationResult object returned in the previous pull.
4. The IM SDK repeats step 3 until the returned value of isFinished is true.

Displaying the conversation information

After obtaining the V2TIMConversation object, the IM SDK displays the conversation information on the UI. V2TIMConversation contains the following key fields, which are often used to construct the conversation list.

Updating the conversation list

After login is successful, the user goes online, or the connection is re-established after being interrupted, the IM SDK will automatically update the conversation list. The update process is as follows:

• When any conversation is updated, such as when a new message is received, the SDK will notify you by using the onConversationChanged event in V2TIMConversationListener.
• When any conversation is added, the SDK will notify you by using the onNewConversation event in V2TIMConversationListener.

To ensure that the order of the conversation list complies with the sequencing principle specified in the last message, the data source must be re-sequenced based on timestamp in lastMessage.

Sample code

The sample code shows how to pull, display, and update the conversation list.

// 1. Set the conversation listener.
[[V2TIMManager sharedInstance] setConversationListener:self];
// 2. Log in to the IM SDK.
[[V2TIMManager sharedInstance] login:@"yahaha" userSig:@"Pass in the actual UserSig" succ:^{
    // 3. Pull 50 local conversations to display them on the UI. Set the value of `nextSeq` that is passed in for the first pull to 0.
    __weak __typeof(self) weakSelf = self;
    [[V2TIMManager sharedInstance] getConversationList:0 count:50
        succ:^(NSArray<V2TIMConversation *> *list, uint64_t nextSeq, BOOL isFinished) {
        __strong __typeof(weakSelf) strongSelf = weakSelf;
        // Pulling is successful, and the UI conversation list is updated.
        [strongSelf updateConversation:list];
        // 4. If more conversations need to be pulled, the value of `nextSeq` returned in the previous pull will be passed in.
        if(!isFinished) {
            [[V2TIMManager sharedInstance] getConversationList:nextSeq count:50
                        succ:^(NSArray<V2TIMConversation *> *list, uint64_t nextSeq, BOOL isFinished) {
                // Pulling is successful, and the UI conversation list is updated.
                [strongSelf updateConversation:list];
            } fail:^(int code, NSString *msg) {
                // The conversation list failed to be pulled.
            }];
        }
    } fail:^(int code, NSString *msg) {
        // The conversation list failed to be pulled.
    }];
} fail:^(int code, NSString *msg) {
    // Login fails.
}];

// Receive the callback for adding a conversation.
- (void)onNewConversation:(NSArray<V2TIMConversation*> *) conversationList {
    [self updateConversation:conversationList];
}

// Receive the callback for updating the conversation.
- (void)onConversationChanged:(NSArray<V2TIMConversation*> *) conversationList {
    [self updateConversation:conversationList];
}

// Update the UI conversation list.
- (void)updateConversation:(NSArray *)convList
{
    // If the updated conversation exists in the UI conversation list, replace this conversation. Otherwise, add this conversation.
    for (int i = 0 ; i < convList.count ; ++ i) {
        V2TIMConversation *conv = convList[i];
        BOOL isExit = NO;
        for (int j = 0; j < self.uiConvList.count; ++ j) {
            V2TIMConversation *uiConv = self.localConvList[j];
            // If the updated conversation exists in the UI conversation list, replace this conversation.
            if ([uiConv.conversationID isEqualToString:conv.conversationID]) {
                [self.uiConvList replaceObjectAtIndex:j withObject:conv];
                isExit = YES;
                break;
            }
        }
        // If the updated conversation does not exist in the UI conversation list, add this conversation.
        if (!isExit) {
            [self.uiConvList addObject:conv];
        }
    }
    // Sort the UI conversation list based on the timestamp in the lastMessage of the conversation.
    [self.uiConvList sortUsingComparator:^NSComparisonResult(V2TIMConversation *obj1, V2TIMConversation *obj2) {
        return [obj2.lastMessage.timestamp compare:obj1.lastMessage.timestamp];
    }];
}

Deleting a Conversation

You can call the deleteConversation API to delete a conversation. This operation cannot be synchronized across multiple devices. When a conversation is deleted, the local historical messages of this conversation are deleted by default.

Only the local historical messages can be deleted. The historical messages in the cloud cannot be deleted. If a deleted conversation is reactivated, historical messages of this conversation can still be pulled from the cloud.

Drafts

When sending a message, the user may need to switch to another chat window before message editing is completed. In this case, call the setConversationDraft API to save the unfinished message. Later, the user can return to the original chat window and call draftText to continue editing the message.

• Only text content can be stored in drafts.
• Drafts are stored only locally, instead of on the server. Therefore, drafts cannot be synchronized across multiple devices. If the program is reinstalled, drafts cannot be reloaded.

FAQs

1. What is the maximum number of conversations that can be stored in a conversation list?

A locally stored conversation list can have an unlimited number of conversations. A conversation list stored in the cloud can have up to 100 conversations.
If the information of a conversation has not been updated for a long time, this conversation will be stored in the cloud for up to 7 days. To adjust the period for storing the conversation, contact us.

2. Why are the conversation lists pulled on different mobile phones in the same account inconsistent?

Locally stored conversations may not always be consistent with those stored in the cloud. If the user does not call the deleteConversation API to delete the local conversations, these conversations will always exist. However, only up to 100 conversations can be stored in the cloud. In addition, if the information of a conversation has not been updated for a long time, this conversation can be stored in the cloud for up to 7 days. Therefore, local conversations displayed on different mobile phones may be inconsistent with each other.

3. Why is the same conversation pulled multiple times?

Conversations that are pulled by the getConversationList API may already have been added to the data source of the UI conversation list through the onNewConversation callback API. Therefore, to avoid adding the same conversation repeatedly, you need to find and replace duplicate conversations based on getConversationID.

4. Does the IM SDK support pinning a conversation to the top of the list?

The IM SDK does not provide the feature of pinning a conversation to the top of the list, but supports re-sequencing of conversations by means of encapsulation. For more information, see the implementation of TUIKit. Such pinning settings take effect only on the local device, and will not be stored on the IM server.