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Send and receive messages

Last updated:2023-01-17 17:39

This document describes how to use the ZIM SDK (In-app Chat) to send and receive messages.


The following shows the access solution that the ZIM SDK provides.


In this solution, you will need to implement the following business logic based on your actual business requirements:

  • The logic for managing the users on the client, and the logic for distributing user ID for users to log in.


Before you begin, make sure:

  • Go to ZEGOCLOUD Admin Console, and do the following:
    • Create a project, get the AppID and AppSign.
    • Activate the In-app Chat service (as shown in the following figure).
  • Xcode 13 or later
  • A real iOS device that is running on iOS 9.0 or later and supports audio and video.

Integrate the SDK

Optional: Create a project

Skip this step if a project already exists.

Create a new project
  1. Open Xcode, and in the Welcome to Xcode window, click Create a new Xcode project or select File > New > Project. In the dialog that appears, select the iOS tab, then select App in the Application section.

  2. Fill in items or choose options for the new project, click Next after configuration is completed.

    Product Name and Organization Identifier are required, which will be used for creating the App UID - Bundle Identifier.

  3. Choose a particular directory to restore the project to be created, and click Create to create a project.

Import the SDK

Choose either of the following methods to integrate the SDK into your project.

Method 1: Integrate the SDK automatically with Swift Package Manager

  1. Open Xcode and click "File > Add Packages..." in the menu bar, enter the following URL in the "Search or Enter Package URL" search box of the "Apple Swift Packages" pop-up window:
  2. Specify the SDK version you want to integrate in "Dependency Rule" (Recommended: use the default rule "Up to Next Major Version"), and then click "Add Package" to import the SDK. You can refer to Apple Documentation for more details.

Method 2: Integrate the SDK automatically with CocoaPods

  1. Install CocoaPods. For more details, see CocoaPods Installation Guide .

  2. Open the Terminal, enter the root directory of the project, and execute the command pod init to create a Podfile.

  3. Open Podfile, add pod 'ZIM', and change MyProject to your target name.

    Because the SDK is XCFramwork, therefore, you will need to use CocoaPods 1.10.0 or later to integrate the SDK.

    target 'MyProject' do
        pod 'ZIM'
  4. Execute pod repo update to update the local index to make sure the latest version of SDK can be installed.

  5. Execute pod install to install the SDK.

    For common problems you may encounter when using CocoaPods, see CocoaPods FAQ .

Method 3: Manually add the SDK to the project

  1. Download the latest version of SDK from SDK downloads.

  2. Unzip the SDK package to the libs folder.


  3. Select the target project, click General, then under Frameworks, Libraries, and Embedded Content, add ZIM.xcframework to the target, and set the Embed field to Embed & Sign.


Implementation steps

Get the sample code

To download and run the sample code, see Sample app.

For the sample code related to this feature, check out the source files in the ZIMExampleLegacy/Peer/ZGPeerChatViewController.m directory in the SDK sample code package.

Import the header file

Import the header file ZIM.h.

#import "ZIM/ZIM.h"

Create a ZIM SDK instance

Creating a ZIM instance is the very first step, an instance corresponds to a user logging in to the system as a client.

So, let's suppose we have two clients now, client A and client B. To send and receive messages to each other, both of them will need to call the create method with the AppID and AppSign you get in the previous Prerequisites steps to create a ZIM SDK instance of their own:

For SDK 2.3.0 or later, the AppSign authentication mode and Token-based authentication mode are both supported.

If you want to change your authentication mode, please refer to the Upgrade the authentication mode from using the AppSign to Token.

// Create a ZIM SDK instance
//  Create a ZIM SDK object and pass your AppID and AppSign.
ZIMAppConfig *appConfig = [[ZIMAppConfig alloc] init];
appConfig.appID = (unsigned int)appID;
appConfig.appSign = @"appSign";
self.zim = [ZIM createWithAppConfig: appConfig];
The sample code to create a ZIM SDK singleton

For most cases, you will only need to create the ZIM SDK instance once. We recommend you create a singleton and save it.

Create a ZGZIMManager class, declare and implement a shared class method in this class, which will create and return a ZGZIMManager object the first time it is called, and create and save a ZIM SDK instance in this object. Then, when you import the zimManager.h header file anywhere in the project and call the [ZGZIMManager shared].zim, a ZIM object will be returned.

#import <Foundation/Foundation.h>
#import "ZIM/ZIM.h"

@interface ZGZIMManager : NSObject
@property (nonatomic, strong) ZIM *zim;
+ (ZGZIMManager *)shared;


#import "ZGZIMManager.h"
static ZGZIMManager *_sharedManager = nil;
@interface ZGZIMManager ()
@implementation ZGZIMManager
+ (ZGZIMManager *)shared {
    if (!_sharedManager) {
        @synchronized (self) {
            if (!_sharedManager) {
                _sharedManager = [[self alloc] init];
                _sharedManager.zim = [ZIM createWithAppID:123]; //Replace the 123 with the AppID you get.
    return _sharedManager;


Conform to the EventHandler protocol

Before a client user's login, you will need to call the setEventHandler method to implement an event handler object that conforms to the ZIMEventHandler protocol (for example, self), and implement the methods involved in the protocol to receive callbacks (you can customize the event callbacks, such as you can receive callback notifications when SDK errors occur or receive message related callback notifications).

The following is the sample code for setting the event callback when connection status changes in the ViewContorller file:


[zim setEventHandler:self];

- (void)zim:(ZIM *)zim errorInfo:(ZIMError *)errorInfo{
    // The callback for receiving error codes. This callback will be triggered when SDK returns error codes.

- (void)zim:(ZIM *)zim tokenWillExpire:(unsigned int)second{
    // The callback for Token expires. This callback will be triggered when the Token is about to expire, and you can customize a UI for this event.
- (void)zim:(ZIM *)zim connectionStateChanged:(ZIMConnectionState)state event:(ZIMConnectionEvent)event extendedData:(NSDictionary *)extendedData {
    // The callback for connection status changes. This callback will be triggered when the connection status changes, and you can customize a UI for this event.

- (void)zim:(ZIM *)zim receivePeerMessage:(NSArray<ZIMMessage *> *)messageList fromUserID:(NSString *)fromUserID {
    // The callback for receiving one-on-one messages. You can receive message notificaitons through this callback after login.

- (void)zim:(ZIM *)zim
    receiveRoomMessage:(NSArray<ZIMMessage *> *)messageList
            fromRoomID:(NSString *)fromRoomID{
    // The callback for receiving the in-room messages. You can receive in-room message notificaitons through this callback after login and joining a room.

- (void)zim:(ZIM *)zim
    roomMemberJoined:(NSArray<ZIMUserInfo *> *)memberList
              roomID:(NSString *)roomID{
    // The callback for a new user joins the room. You can receive notifications when a new user joins the room through this callback after logging in and joining a room.

- (void)zim:(ZIM *)zim
    roomMemberLeft:(NSArray<ZIMUserInfo *> *)memberList
            roomID:(NSString *)roomID{
    // The callback for an existing user leaves the room. You can receive notifications when an existing user leaves the room through this callback after login and joining a room.

Log in to the ZIM SDK

For client A and client B to send and receive messages after creating the ZIM SDK instance, they will need to log in to the ZIM SDK.

To log in, Clients A and B both need to do the following:

  1. Call the ZIMUserInfo method to create a user object.
  • You can custom the userID and userName, and we recommend you set these two to a meaningful value and associate them with the account system of your application.

First, create a ZIMUserInfo object with your user information. Then, client A and client B can call the login to log in to the ZIM SDK.

// userID must be within 32 bytes, and can only contain letters, numbers, and the following special characters: '~', '!', '@', '#', '$', '%', '^', '&', '*', '(', ')', '_', '+', '=', '-', '`', ';', '’', ',', '.', '<', '>', '/', '\'.
// userName must be within 64 bytes, no special characters limited.
ZIMUserInfo *userInfo = [[ZIMUserInfo alloc]init];
userInfo.userID = @"zegoUser1"; // Fill in a NSString type value.
userInfo.userName = @"zegotest";// Fill in a NSString type value.

// When logging in: 
// If you are using the Token-based authentication mode, you will need to fill in the Token which you generated by referring to the [Authentication] doc.
// If you are using the AppSign mode for authentication (the default auth mode for v2.3.0 or later), leave the Token parameter blank. 

[zim loginWithUserInfo:userInfo callback:^(ZIMError * _Nonnull errorInfo) {
    // Implement a callback for login here.

Send messages

Client A can send messages to client B after logging in successfully.

Currently, the ZIM SDK supports the following message types:

Message type Description Details
Text message. Size limit: 32 KB. Rate limit: 10 requests/second.
Enable messages to be more deliverable, and can be stored as message history. Suitable for one-on-one chat and group chat.
Customizable signaling message. Size limit: 5 KB. Rate limit: 10 requests/second.
Supports massive concurrency. Suitable for live audio room, online classroom, the messages won't be stored after the room is destroyed.
In-room barrage message (bullet) screen message). Size limit: 5 KB. No specific rate limit.
The high-frequency messages that don't require 100% deliverability, this message type is often used to send bullet screen messages.

Supports massive concurrency, but the message deliverability can't be guaranteed.

Image message. Supports major image formats, including JPG, PNG, BMP, TIFF, and GIF. Size limit: 10 MB. Rate limit: 10 requests/second.
Enable messages to be more deliverable, and can be stored as history messages. Suitable for one-on-one chat, room chat, and group chat.
File message. Supports files in any format. Size limit: 100 MB. Rate limit: 10 requests/second.
Voice message. Supports voice messages in MP3 format within 300 seconds. Size limit: 6 MB. Rate limit: 10 requests/second.
Video message. Supports video messages in MP4 or MOV format. Size limit: 100 MB. Rate limit: 10 requests/second.

To send one-to-one messages, for example, client A wants to send a message to client B, then client A needs to call the sendMessage method with client B's userID, message content, and other info. And client A can be notified whether the message is delivered successfully through the callback ZIMMessageSentCallback.

  • onMessageAttached callback: The callback on the message not sent yet. Before the message is sent, you can get a temporary ZIMMessage message for you to implement your business logic as needed. For example, you can get the ID of the message before sending it. Or when sending a message with large content, such as a video, you can get the localMessageID of the message before the message is uploaded to implement a Loading UI effect.
// The following shows how to send one-to-one message, the [conversationType] needs to be set to [ZIMConversationTypePeer].
ZIMTextMessage *zimMessage = [[ZIMTextMessage alloc]init];
zimMessage.message = @"Message content";
ZIMMediaMessageSendNotification *notification = [[ZIMMediaMessageSendNotification alloc] init];
notification.onMessageAttached = ^(ZIMMessage * _Nonnull message) {
    // The callback on the message not sent yet. You can get a temporary object here and this object must be the same as that created zimMessage object. You can make your own business logic using this as needed, for example, display a UI ahead of time.
ZIMMessageSendConfig *config = [[ZIMMessageSendConfig alloc] init];
config.priority = ZIMMessagePriorityMedium;  // Set priority for the message. 1: Low (by default). 2: Medium. 3: High.

// In 1-on-1 chats, the conversationID is the peer user ID. In group chats, the conversationID is the groupID. In the chat room, the conversationID is the roomID.
[zim sendMessage:zimMessage toConversationID:conversationID conversationType:ZIMConversationTypePeer config:config notification:notification callback:^(ZIMMessage * _Nonnull message, ZIMError * _Nonnull errorInfo) {
    // Implement the event callback on message sent.
    // toUserID refers to the userID of the message receiver.

### Receive messages

After client B logs in, he will receive client A's message through the callback [`receivePeerMessage`\|_blank](/article/api?doc=zim_API~objectivec_ios~protocol~ZIMEventHandler#zim-receive-peer-message-from) which is already set in the [`setEventHandler`\|_blank](/article/api?doc=zim_API~objective-c_ios~protocol~ZIM#set-event-handler) method.

<div class = 'mk-warning'>

When a message is received, you need to determine the message is a Text message or a Command message because these two message types are based on the basic message. You need to convert the basic message class to a concrete message type and then retrieve the message content from the `Message` field.

- (void)zim:(ZIM *)zim
    receivePeerMessage:(NSArray<ZIMMessage *> *)messageList
            fromUserID:(NSString *)fromUserID{
          for(ZIMMessage *message in messageList){
        if (message.type == ZIMMessageTypeText){
            ZIMTextMessage *textMessage = (ZIMTextMessage *)message;
        else if (message.type == ZIMMessageTypeCustom){
            ZIMCustomMessage *customMessage = (ZIMCustomMessage *)message;

Log out

For a client to log out, call the logout method.

[zim logout];

Destroy the ZIM SDK instance

To destroy the ZIM SDK instance, call the destroy method.

[zim destroy];
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